By Brian Wacker, PGATOUR.COM

NEWTOWN SQUARE, Pa. -- Adam Scott and Hunter Haas share the lead at 4 under after the first round of the AT&T National. Here’s a look at some key numbers from each of their rounds:

Adam Scott

Scott’s 66 equals his low round on the PGA TOUR in 2011, which he previously shot in the opening round of the Crowne Plaza Invitational at Colonial.

Scott holds the lead/co-lead after the first round for the seventh time in his TOUR career and for the first time since the 2008 Shell Houston Open (WD due to illness after second round). He has converted just one of his previous six first-round leads/co-leads in to victory, winning by one at THE PLAYERS Championship in 2004.

Entering this week, Scott has made 6-of-10 cuts on TOUR in 2011 with his best result a tie for second at the Masters. His only other top-10 on the season was a tie for sixth at the World Golf Championships-Cadillac Championship. Scott is in search of his eighth-career TOUR victory and first since the 2010 Valero Texas Open.

In his only previous appearance at the AT&T National Scott missed the cut in 2007.

Hunter Haas

It represents the second time in his TOUR career he has held the lead/co-lead after 18 holes. Haas led the 2005 Children’s Miracle Network Classic after the first round en route to a tie for 58th.

Haas’ round was highlighted by a string of four consecutive birdies from Nos. 13-16, his front nine, as he went out in 31. His only blemish on the day was a bogey at the par-4 seventh.

In 19 starts on TOUR this year, Haas has made 12 cuts and posted one top-10, a tie for third at the Puerto Rico Open. His 66 represents his lowest opening-round score on TOUR in 2011, bettering a pair of 67s carded at the Bob Hope Classic and Puerto Rico Open.

In his third full season on the PGA TOUR (2001, 2005 and 2011), Haas had made 85 starts entering this week with his best result the tie for third earlier this year in Puerto Rico.

NETOWN SQUARE, Pa. -- Aronimink continues to prove difficult -- only 30 players are under par at the moment.

One of those is Hunter Haas, who is 5 under and atop the leaderboard. Haas is bogey free and at one point made four straight birdies on Nos. 13 through 16 (he started on the back nine).

Haas has missed three of his last four cuts, but he has his game working here. Haas is fourth in putting and seventh in the field in greens in regulation.

Elsewhere on the leaderboard, Adam Scott is 3 under as he finishes up his round, while Vijay Singh has fallen back to 2 under. Also at 2 under is Rickie Fowler, who just finished off his 68