Michael Allen shot a course-record 10-under 61 on Saturday to take a one-stroke lead over defending champion John Cook in the season-ending Charles Schwab Cup Championship.
The 51-year-old Allen had 10 birdies, the last on the par-4 18th, in his bogey-free round at Harding Park for the lowest round of his career. He also matched the best round of the year on the Champions Tour.
"I got off to a good start ... and I just kind of kept going," said Allen, who had a 14-under 199 total. "I had some nice shots and I finally read a couple of putts right and got them to go in. I was feeling pretty good with the putter."
Cook, the winner last year at Sonoma Golf Club, shot a 67.
David Frost (65) was two back at 12 under.
Schwab Cup points leader Bernhard Langer (67), Russ Cochran (68) and Tom Lehman (69) were 10 under.
Fred Couples (70) was 5 under, all but ending his chances of catching Langer in the two-man Schwab Cup race for the $1 million annuity. If Couples rallies to win Sunday, Langer would still take the top prize with a two-way tie for fourth or better.
Allen entered the day five shots behind Cook and had just seven birdies in the first two rounds. He birdied three of the first four holes Saturday, closed the rounds with four more over the final six.
The 61 broke the course record of 64 set by Colin Montgomerie in the 2005 WGC-American Express event. Ken Venturi also shot 64 at Harding Park before the course was restructured.
It's also the lowest score ever posted in the Charles Schwab Cup Championships, breaking Cook's year-old mark of 62.
Cook, who has three runner-up finishes this year, was stunned at Allen's day.
"I didn't see 10 under out there today, I can promise you that," Cook said. "I played pretty good and got clipped by six."
Allen grew up in the Bay Area, his mother still lives in the area and he spent the past week visiting many friends, several of whom lined the 7,135-yard course at Harding Park.
"This whole tournament being here in San Francisco is special to me," said Allen, the 2009 Senior PGA Championship winner. "I got here in time for the Giants' win, which was phenomenal. It's been a great week for me."
Cook posted his eighth consecutive round in the 60s but trails Cook after leading each of the first two days. Cook birdied the par-5 10th to get to 4 under on the day, then parred out, missing a 10-foot downhill putt on No. 18 that would have tied him for the lead.
Players were allowed to lift, clean and place their golf balls because of the conditions of some of the fairways. With rain forecast for early afternoon Sunday in the Bay Area, things could get tougher.
"Hopefully the course will drain enough that you can find some spots to put the ball," Cook said. "The greens will be fine ... unless it just hammers down rain. These greens will be fine but the fairways will be difficult."
The weather didn't bother Frost, who birdied five of the first seven holes on the back nine. That got Frost to 13 under but a bogey on No. 18 dropped him two strokes off the pace.
Langer was in position to make a run Sunday as well. The points leader overcame a bogey on No. 2 and matched his best round of the tournament while pulling within four shots of the lead.
Couples hoped to become only the second player in tour history to overtake the points leader in the final tournament. Tom Watson did it in 2005 when points were tripled in the Schwab Cup Championship.
Instead, Couples has struggled to even stay close to Langer. His 70 on Saturday included only two birdies and one bogey.