Updated

Edmond, OK (SportsNetwork.com) - Colin Montgomerie carded an even-par 71 on Friday and kept his 1-stroke lead through two rounds of the U.S. Senior Open.

Montgomerie, the reigning Senior PGA Championship winner, finished 36 holes at Oak Tree National at 6-under-par 136.

"It's a long way (to the end)," Montgomerie said. "I look forward to getting in a position to contend for tomorrow evening and I'm playing well. It's just a matter of trying to be as patient as possible and let things happen. But it's not easy out there, not easy."

Scott Dunlap shot a 3-under 68 to jump into second place at 5-under 137 while 2010 U.S. Senior Open champion Bernhard Langer (69) and Gene Sauers (69) shared third at minus-4.

Mark Brooks (71), Lance Ten Broeck (69), Jeff Sluman (69) and Doug Garwood (69) are tied for fifth at 3-under. Vijay Singh (71) is alone in ninth at 2- under 140.

Montgomerie parred his first two holes before tripping to bogeys at the third and sixth to fall to 4-under and hand the outright lead to Dunlap, who had set the clubhouse mark at 5-under earlier in the day.

Montgomerie bounced back with a birdie at the seventh to reclaim a share of the lead. He then reeled off nine straight pars before recording a 4-foot birdie at the par-3 17th to move back into sole possession of the lead.

"I got off to a poor start, to be honest," said Montgomerie. "It's not easy to repeat a good round as yesterday's was but this was as good, to be honest. Seventy-one out there was a good effort."

Dunlap started on the 10th tee and parred his entire outward nine before doing all of his scoring around the turn.

He picked up his first shot with a birdie at the second and after parring the next two holes, rolled in birdies at the fifth and seventh to reach 5-under.

Dunlap parred his final two holes to claim the clubhouse lead.

"I have been particularly good with the putter this week. Been tidy, I have made a couple, made all my short ones," Dunlap said. "That's what a guy does to win something like this."

Langer birdied the fourth, seventh and eighth to reach 5-under. After posting a bogey at the 10th, he birdied the 12th and 14th to move to 6-under and claim the outright lead.

But he tripped to bogeys at the 15th, 16th and 18th around a birdie at the 17th to fall two shots off the pace.

Sauers countered three bogeys with an eagle and three birdies to earn his share of third place.

NOTES: Montgomerie's win at the Senior PGA was his first major championship win on any tour, and his first win in the United States ... Montgomerie has eight top-10 finishes in his 10 previous Champions Tour starts this year ... Langer posted an under-par round for the 35th time in 38 rounds this year ... The cut line fell at 7-over 149 with 66 players advancing to the weekend, including amateurs Jeff Wilson (146) and Mike McCoy (148).