Updated

Bridgend, Wales (SportsNetwork.com) - Bernhard Langer expanded his lead to seven shots heading into the weekend at the Senior Open Championship following his second-round, 5-under 66 on Friday.

Langer, who is seeking his four career major championship on the Champions Tour and his second this season, is at 11-under-par 131 through 36 holes and he stands seven shots ahead of Chris Williams and Colin Montgomerie, this year's Senior PGA Championship and U.S. Senior Open Championship winner.

The 7-shot lead by Langer is the largest in this championship's history, beating Noboru Sugai's 4-shot lead at Royal County Down in 2002. Langer's 11- under through 36 holes also ties a record set by Fred Funk at Sunningdale in 2009.

"I can't remember if I've had any similar rounds in the past, but it's definitely very, very good golf," Langer said. "To make two bogeys, but more importantly, 13 birdies along with it is not easily done in these conditions."

Montgomerie matched Langer's round with a 5-under 66, while Williams finished day two with a 70. Both Montgomerie and Williams are 4-under 138 at Royal Porthcawl Golf Club.

Pedro Linhart sits alone in fourth place at 3-under 139 after his second-round 69. He is followed by eight-time PGA major champion Tom Watson (66) and Bob Tway (73), both of whom are at 2-under 140.

Barry Lane (69) and Rick Gibson (71) are the only other players in the field under par through two rounds. They are tied for seventh at 1-under.

Langer began his day two shots ahead of Tway, and the German started things off on the wrong foot with a bogey at the first. Langer quickly rebounded, however, and he started to widen the gap.

The 56-year-old followed the bogey with back-to-back pars before pouring in three straight birdies from the fourth to put him at minus-2 on the day. Langer rounded out his front nine with three straight pars.

Another par at No. 10 preceded back-to-back birdies at 11 and 12 as Langer continued to increase his lead. Langer made five straight pars from 13 before finishing his day with his sixth birdie of the round at the last.

"I played very smart, very aggressive, then very smart and I was fortunate to some extent, but I have played very well the last two days," Langer said. "It wasn't the kind of start I wanted today, but from that point on, I settled down and I played some really good golf."

Montgomerie, who started the day at 1-over and seven shots off the lead, did not do much to help himself at the beginning of his round. Two straight bogeys at one and two put Montgomerie in a hole, one he quickly dug out of.

The 51-year-old Scotsman made six birdies in a 7-hole span, with the lone par coming at No. 4. All of a sudden Montgomerie was 3-under for the week as he made the turn. He made two more birdies at 13 and 18 to go along with a bogey at 16, putting him in a tie for second.

Williams also started off with a bogey at No. 1, but a birdie at No. 2 got him back to even-par. A bogey at No. 8 dropped him back to 1-over and he made the turn there.

An eagle at 11 and a birdie at 13 had Williams rolling, but a bogey at 17 put him back to 1-under on the day. He ended there with a par at No. 18.

NOTES: Langer is seeking his second win at this championship, having won it back in 2010 ... Watson is a three-time winner of this championship with victories in 2003, 2005 and 2007 ... Miguel Angel Jimenez (69), who is 1-over on the week, began and ended his day with eagles at one and 18 ... With the cut at 7-over 149, 76 players advanced to the weekend ... Among those that missed the cut were Des Smyth, Corey Pavin, Eduardo Romero, Mark James, last year's winner Mark Wiebe and Craig Stadler.