OMAHA, Neb. (AP) -- It's never been so crowded at the top of the U.S. Senior Open leaderboard.
When Tom Lehman chipped in from 45 feet on the 18th hole Thursday, he joined six others at 3-under 67 for the first round at the Omaha Country Club.
There had never been as many as seven co-leaders after the opening round of the event. The previous record was five in 1997.
"In one round, 18 holes, it's like a sprint," Lehman said. "Over the course of four rounds, which is more like a marathon, things really do spread out. The field will thin out."
Kenny Perry shot a 67 in the morning, putting together a solid start in his bid for a second straight win in a senior major. Michael Allen and Jay Don Blake also were 3 under after their morning rounds, and Gary Hallberg, Mark O'Meara, Fred Funk and Lehman came in with the same score in the afternoon.
The hilly 6,700-yard course took a toll on the field of golfers age 50 and older, especially in the afternoon as temperatures reached the upper 80s with a light breeze. The small and undulating greens browned up in the heat and proved dicey.
"When you get tough conditions and you're playing good, you get rewarded," Funk said. "More than likely, the guy that's playing the best in these kind of conditions will be at the top. Hopefully, it will be me."
Perry, who won the Senior Players Championship two weeks ago at Fox Chapel, Pa., made five birdies against two bogeys.
The season points leader started on the back nine and had birdies on three of his first eight holes. He hit an 8-iron to within 10 feet on the par-3 11th, drove the green on the 312-yard, par-4 13th, and hit hybrid-pitching wedge on the 319-yard, par-4 17th and made his 15-foot putt.
He birdied both par-5s on his second nine, but came away a bit disappointed after missing a 5-foot eagle putt on No. 6.
"I took care of the par 5s today and drove it nicely, kept it in the fairway, kept it in play," Perry said. "Like I said yesterday, if I hit it in the fairway, I really like my chances on this golf course."
Lehman, the 2012 Champions Tour points and money leader, overcame a bogey on No. 8 with three birdies on the back nine -- none bigger than the one on 18.
His second shot came to rest in thick grass to the right of the green. He used an 8-iron for his chip and watched it roll downhill slowly into the cup for what ranked as the shot of the day.
"The lie was a little bit squirrely," Lehman said. "The grass was growing against the ball so it's easy to kind of not catch it cleanly. I took less loft and kind of hit it a little bit thin. Once it gets out on the green, it's going to get down there."
Chien Soon Lu, Peter Senior, Rocco Mediate and 2010 champion Bernhard Langer shots 68s. Colin Montgomerie, who turned 50 last month and is playing in his second senior event, was in a pack that was two shots behind.
Defending champion Roger Chapman struggled with his putter and was seven shots behind after a 74.
Tom Watson, who played with Langer and Montgomerie and drew the largest galleries of the day, struggled with his irons while shooting a 70 that included one birdie and one bogey.
"I hit a few good shots today, but for the most part, my shots weren't very solid," Watson said. "One good thing about it was that I got about the best score I possibly could out of my round."
Fred Couples, coming off three straight runner-up finishes on the Champions Tour, had a 1-over 71.
Couples, like others, had difficulty figuring out the speed of the greens. The recent heat wave has put stress on them, and warmer temperatures are forecast this weekend.
"They're suffering," Lehman said. "And there's differing kinds of grass. That's probably the biggest thing. It's not 100 percent pure. So the heat affects them each differently, which is why you see that spotty stuff. That kind of makes the putts really not quite as true as you would hope for."