By Brian Wacker, PGATOUR.COM

Dustin Johnson withdrew from the HP Byron Nelson Championship on Tuesday, citing a bad back.

It marks the third straight week Johnson has missed because of injury.

Johnson withdrew from the Wells Fargo Championship because of inflammation in his left wrist. After an opening-round 74 at last week's PLAYERS Championship, Johnson withdrew, citing an injury to his lower back.

Tuesday, Johnson said via his Twitter account, "Tried to go but have inflammation in my facet joints. Some rest and daily therapy with my physical therapist, then I should be good!!"

Johnson opened the year with a victory in Maui. He pulled out of the following week's event on Oahu after the first round with the flu. He had recorded three straight top-15 finishes before pulling out at Quail Hollow.

Earlier Tuesday, Bob Estes also withdrew from the HP Byron Nelson Championship.

Each week, PGATOUR.COM's Fantasy Insider Rob Bolton offers his Power Rankings for the weekly TOUR event as well as his Sleeper picks. But what about the players who don't make the Power Rankings but who can't really be considered Sleepers? Bolton will make one "wild card" selection from the large group of players who fall into that middle range but might rise up to claim the title. This week's pick is ...

DUSTIN JOHNSON

Injuries to his left wrist and lower back have limited his action the last two weeks. They're also the reason why he didn't crack the Power Rankings. Strung together three straight top 15s through the Masters. He's 4-for-4 at TPC Four Seasons with a T4 in 2009, T7 in 2010 and T20 in 2011. Under par in nine of his last 12 rounds on the course. Currently 53rd on TOUR in greens in regulation, 32nd in strokes gained-putting and 26th in adjusted scoring.

POWER RANKINGS: To read Bolton's top 15 for TPC Four Seasons, click here.

PONTE VEDRA BEACH, Fla. -- Dustin Johnson has withdrawn from THE PLAYERS Championship citing a lower back injury. 

Johnson shot a 2-over 74 in his first round at TPC Sawgrass. He was playing with Ernie Els and Billy Horschel (Watch their round live here). 

Felt good working out this morning but something didn't feel right on the range before the round. Hoping to rebound at the @hpbnc!!

— Dustin Johnson (@DJohnsonPGA) May 10, 2013

Guan has made the cut in both his starts on the PGA TOUR this season. (Revere/Getty Images)

By Brian Wacker, PGATOUR.COM

Guan Tianlang, the 14-year-old Asia-Pacific Amateur Champion who made history earlier this month by becoming the youngest player to play in and make the cut at the Masters, has accepted a sponsor exemption to play in the HP Byron Nelson Championship, tournament officials announced Tuesday.

"What Guan has been able to accomplish at such a young age is very impressive," tournament chairman Mike McKinley said.  "We have always had a tradition of identifying young talent and giving them an opportunity to compete at the Nelson, and we look forward to continuing that with Guan."

Guan captured low amateur honors at the Masters. He also made the cut at last week's Zurich Classic of New Orleans.

Dustin Johnson and Marcel Siem committed to play at TPC Four Seasons Las Colinas, May 13-19.

Johnson was scheduled to play in this week's Wells Fargo Championship but withdrew because of a sore wrist.

Dustin Johnson has withdrawn from the Wells Fargo Championship, citing an irritated left wrist.

He will be replaced by Paul Haley II, who spent last season on the Web.com Tour. This year, he's missed seven of eight cuts on the PGA TOUR.

Johnson, meanwhile, has played well of late, finishing in the top 15 in each of his last three starts, which included a tie for fourth in Houston and a tie for 13th at the Masters.

In three previous trips to Quail Hollow, Johnson twice missed the cut.

His next start is expected to be THE PLAYERS Championship.

By Brian Wacker, PGATOUR.COM

AUGUSTA, Ga. -- The first round of the Masters always provides plenty of entertainment and storylines, and Thursday was no exception.

Whether it was 53-year-old Fred Couples turning back the clock (again), or 14-year-old Tianlang Guan shooting 73, or Sergio Garcia grabbing a share of the lead at a place where a year ago he said he didn't have it in him to win a major, there was a lot to soak up.

Friday, however, is more serious with players positioning for the weekend. With that in mind, here are a few groups to keep an eye on in the morning wave.

Tianlang Guan, Ben Crenshaw, Matteo Manassero, 9:06 a.m.: "Very, very impressive" is how Crenshaw described the teenager's performance in the opening round. A former phenom himself, that's not hyperbole from the former Masters champ. Guan had the best score of the six amateurs in the field and now has a chance to make it to the weekend.

Sergio Garcia, Adam Scott, Angel Cabrera, 9:39 a.m.: Garcia shot 66 in the opening round, matching his career low here, and recorded his first bogey-free round here since 2002. It's the first time he's led after any round of the Masters; now the question is can he keep it going? He's 1-for-9 in his career in converting first-round leads into wins on the PGA TOUR.

Dustin Johnson, Fred Couples, Branden Grace, 9:50 a.m.: Johnson said Thursday that Augusta National suits his eye. It looked like it. He shot 67 and is one off the lead entering the second round. The key for him: Putting. Johnson took just 26 putts in the first round. Meanwhile, for all of Couples' success here, Thursday was just the fifth time he's cracked 70 in the opening round. That bodes well for him the rest of week -- he has 11 career top 10s here and in each of the last three years has finished in the top 15. He always feels ageless here and fed off Johnson, a sort of younger version of himself. There's no reason to think he can't again.

Phil Mickelson, Louis Oosthuizen, Martin Kaymer, 10:23 a.m.: Mickelson admitted to being too "tentative" in his opening-round 71. Translation: With a wet and soft golf course, and 33 players breaking par in the opening round, Mickelson is going to be very aggressive on Friday.

Rory McIlroy, Keegan Bradley, Freddie Jacobson, 10:34 a.m.: McIlroy's opening round was a mess, but he held it together well enough to shoot even par. He'll have to clean up his putting, however, if he's going to get in contention for the weekend. Ditto Bradley, who had 30 putts and an up-and-down day but managed to scrape out a couple of birdies on his way to a 73.

Johnson had just 26 putts in Thursday's opening round. (Ehrmann/Getty Images)

By Brian Wacker, PGATOUR.COM

AUGUSTA, Ga. -- Dustin Johnson thinks Augusta National suits his game.

The results, however, have dictated otherwise. In three trips down Magnolia Lane, he's never finished higher than 30th. After a 5-under 67 to get within one of the lead on Thursday, however, he hopes to change that.

"This is one of those courses, the more you play it, the more you get to know it," Johnson said. "You kind of know where you need to hit it so you can actually have a chance to get up‑and‑down or you know what side of the fairway to miss it on at certain flags."

He didn't miss much in the opening round this year.

Johnson had four birdies, an eagle and just one bogey. He also hit 13 greens and took just 26 putts.

Two of those birdies came in Johnson's first two holes, which included a chip-in on No. 1. He added another chip-in for birdie on the par-4 ninth, then reached the par-5 13th in two and made the 15-foot putt for eagle.

Johnson is back at the Masters after missing it due to a back injury last year.

"I've played OK here in the past, just not great," Johnson said. "Not playing last year, and then coming back this year and getting a good round is really good. It feels good."

So does how Augusta National fits his eye.

"I love the shape of all the holes," he said. "The par 5s are all reachable, depending on which way the wind is blowing, with pretty short irons, except for 8."

He played them in a combined 4 under with two birdies, an eagle and a par.

As for why he hasn't had better results here?

"It's just a tough golf course to figure out like where to hit it, and using slopes, and then certain putts you have," he said. "Like I said, you learn something new around here every day you play it."

Thursday, it looked like Johnson learned a lot.

Johnson currently ranks sixth in FedExCup standings. (Chris Condon/PGA TOUR)

Each week, PGATOUR.COM's Fantasy Insider Rob Bolton offers his Power Rankings for the weekly TOUR event as well as his Sleeper picks. But what about the players who don't make the Power Rankings but who can't really be considered Sleepers? Bolton will make one "wild card" selection from the large group of players who fall into that middle range but might rise up to claim the title. This week's pick is ...

DUSTIN JOHNSON

It seems impossible that he wouldn't crack a Power Rankings that goes 20 deep, but this is the reality in a field that boasts several that have enjoyed more consistent seasons thus far on top of success at the Masters. This is DJ's fourth appearance at Augusta National. (He withdrew early last year due to a back injury.) In 12 rounds, he's broken 70 just once and hasn't finished better than T30 in his debut in 2009. After opening this year with a victory at Kapalua, he went six straight starts without a top 30, but reversed his fortune with a T12 at the WGC-Cadillac and a T4 in Houston. Ranks 33rd on the PGA TOUR in greens in regulation, 32nd in strokes gained-putting and 21st in adjusted scoring.

POWER RANKINGS: To read Bolton's top 20 for Augusta National, click here.

Henrik Stenson ranks first in four major statistical categories in 2013. (Halleran/Getty Images)

By Bill Cooney, PGATOUR.COM

D.A. Points won the Shell Houston Open with a clutch 13-foot par putt on the 72nd hole on Sunday. Everyone will remember the story about Points using his mom's old putter. But don't forget about those wedges (we're pretty sure those aren't from mom, too). Points' scrambling was pretty tidy in Houston, especially in comparison to his stats from this season. We'll take a look at that and also this week's Valero Texas Open -- played at difficult TPC San Antonio -- by going inside the numbers.

1st  Ranking next to Henrik Stenson’s name in four major statistical categories in 2013. … Stenson, who ranked 133rd in the world just eight months ago, has really turned his game around. He’s played five events in ’13 (four stroke play) and ranks first in driving accuracy (72.96 percent), greens in regulation (77.78 percent), scrambling (75 percent) and total driving. And now -- buoyed by a T2 at the Shell Houston Open, he’s headed to the Masters.

+1.989  That’s how many average strokes TPC San Antonio played over par at the 2012 Valero Texas Open. The AT&T Oaks Course was the fourth most-difficult course on the PGA TOUR last season. It was also the seventh most-difficult on TOUR in 2011 (+1.665). … There have been several renovations to the golf course in preparation for this week’s tournament -- in which Rory McIlroy is playing for the first time -- which includes alterations to the first, fourth, 10th and 12th greens.

6  This number is a reason to keep an eye on Ben Curtis at this week’s Valero Texas Open. It represents the number of defending champions from 2012 that have posted top-five finishes in 2013. Steve Stricker (2nd at Hyundai Tournament of Champions), Brandt Snedeker (T2 at Farmers Insurance), Bill Haas (T3 at Northern Trust), Hunter Mahan (WGC-Accenture Match Play), Luke Donald (T4 Tampa Bay Championship presented by EverBank) and Tiger Woods (Win at Arnold Palmer Invitational presented by MasterCard) have carded T5s. Of course, four defending champs have missed weekend play. … Curtis, defending this week at TPC San Antonio, missed the weekend in Houston and has just a pair of T25s this season. So will it be feast or famine for him this week?

9  Number of eagles made this season by Chris Kirk, which leads the TOUR. … Yes, Kirk has an incredible nine eagles in 31 rounds. Not bad, considering Charles Howell III led the TOUR last season with 18 eagles in 98 rounds. Even more ridiculous, Kirk hasn’t even had an eagle in his past two tournaments or eight rounds. He had three eagles at the Sony Open in Hawaii and three at the Northern Trust Open. He also had a hole in one at the Humana Challenge in partnership with the Clinton Foundation. It’s even more impressive when considering a player such as Lee Westwood has no eagles in 2013.

12 of 15  For you non-math majors that comes out to 80 percent, or Points’ scrambling percentage at Shell Houston, which ranked fifth in the field. … This essentially helped Points win his second career event on TOUR, as you may recall his incredible saves on the 17th and 18th holes in the final round. He got up-and-down from 43 yards out on 17 and made a 13-foot, 5-inch putt on the 18th to win. The 80 percent clip is also a dramatic improvement for Points. In 2013, Points ranks 116th in scrambling at 57.56 percent. He was T112 in 2012, at 56.50 percent.

146th  Scrambling rank for Dustin Johnson in 2013, or a rate of 55 percent. … What’s the big deal, you ask? No, Johnson wouldn’t be a top pick to win a short-game contest on TOUR. But last season, he had improved dramatically from past years. He ranked 32nd in scrambling at 60.29 percent and 38th in sand saves at 53.85 percent. Not bad, considering the best he ranked in scrambling from 2008 to ’11 was 139th. Johnson has just three T25s in nine events in ’13, but poor scrambling stats haven’t affected Johnson much during his career. We’ll have to see if it affects him in '13.

169 feet, 4 inches  Distance in putts made for Points in the first round of Shell Houston. … Points needed just 23 strokes on the greens during a first-round, 8-under 64. He gained nearly 5 strokes on the field average during Round 1. Points cooled off a bit on the greens, but finished the week 10th in strokes gained-putting. For 2013, Points ranks 152nd in SGP -- the reason he sought help with his putting and added his mom’s old putter to his bag.

INSIDE THE NUMBERS ARCHIVE

Week 2: Sony Open/Humana Challenge

Week 3: Humana Challenge/Farmers Insurance Open

Week 4: Farmers Insurance Open/WM Phoenix Open

Week 5: WM Phoenix Open/AT&T Pebble Beach National Pro-Am

Week 6: AT&T Pebble Beach National Pro-Am/Northern Trust Open

Week 7: Northern Trust Open/WGC-Accenture Match Play

Week 8: WGC-Accenture Match Play/The Honda Classic

Week 9: The Honda Classic/WGC-Cadillac Championship

Week 10: WGC-Cadillac/Tampa Bay Championship

Week 11: Tampa Bay Championship/Arnold Palmer Invitational

Week 12: Shell Houston Open

By PGATOUR.COM staff

Dustin Johnson put together an incredible final round at the Shell Houston Open. It just wasn't quite enough.

Johnson used an eagle at the par-5 15th (watch above) en route to a 7-under 65 to post 14 under on Sunday. He was one shot behind co-leaders D.A. Points and Billy Horschel when he finished. However, Henrik Stenson posted 15 under shortly after.

Johnson, who missed cuts in his only two previous appearances at Redstone in 2008 and '09, carded seven birdies, an eagle and two bogeys on his round and is currently tied for third place.

Despite admitting that he left some shots on the golf course, Johnson said he was pleased with his performance -- his last before the Masters.

"I knew I was going to have to come out and do something special today if I wanted to even have a chance," Johnson said. "I played really well, 7-under on Sunday, I'll take that anywhere, anytime, and be happy with it. You know, obviously I left a few shots out there, but, you know, that's golf."