Houston - Phil Mickelson shot his lowest round in two years on Saturday, tying the course record with a 9-under 63 to share the lead with Scott Verplank after three rounds at the Houston Open.
Verplank shot his second straight 65 to catch Mickelson at 13-under par.
Australian Aaron Baddeley (66) and second-round leader Chris Kirk (69) were one stroke back, and defending champion Anthony Kim and David Hearn (66) two two behind.
Mickelson, the defending champion at next week's Masters, equaled the record score set by Johnson Wagner and Adam Scott in 2008 and matched by Jimmy Walker on Thursday. It was Mickelson's best score since a 62 in the third round at the 2009 Northern Trust Open, which he won.
"To get a good round like this means a lot," Mickelson said. "Also, to have the challenge to be in contention, to be in the final group, have an opportunity to win, I really enjoy that opportunity. I think it's good for me to be in that position heading into next week, too."
Mickelson has won the last four events during which had a round of 64 or better, dating to the 2006 BellSouth Classic. That year, he earned his second green jacket the following week and is the last player to win the event before Augusta and the Masters in the same year.
The Houston Open became the run-up tournament to the Masters in 2007, and Mickelson is here for the fourth straight year. He practiced at Augusta earlier this week, and only arrived in Houston on Wednesday, bypassing the chance to play warmup rounds at Redstone.
He said winning the week before the '06 Masters gave him a valuable boost, and he sees no disadvantage in trying to duplicate that feat.
"People have talked about winning the week before a major as not necessarily the greatest thing, because it takes away energy, or what have you," Mickelson said. "I felt like in '06, it was really a benefit to gain the momentum and confidence of winning a golf tournament right before, especially the Masters."
Organisers have tried to groom the Redstone course to simulate the conditions players will see next week, and Mickelson said that creates a smooth transition to Augusta.
But Mickelson is more concerned this weekend with improving his shot visualisation than practicing shots he'll see at the Masters. He had shot only four sub-70 rounds in his previous four events.
"What I'm working on is what I did best today, which was really seeing the shot and executing and holding that picture throughout the swing," Mickelson said. "I probably did that better today than I have in a long time."
Mickelson switched between two drivers - with different lengths and lofts - on the practice range before his round. He's leaning toward having both in his bag at Augusta next week.
"There's a good chance I'll have that," Mickelson said.
Mickelson birdied three of his first four holes on Saturday, under cloudy skies with virtually no wind.
Paired with Lee Westwood, he lost his tee shot left on No. 6, a dogleg left. Mickelson took a drop out of a native area, but then saved par by holing a 50-yard pitch from behind the green.
When the ball disappeared, Westwood's caddie, Billy Foster, kneeled and bowed to Mickelson in joking homage as the huge gallery exploded into a loud roar.
"It could've really been bad," Mickelson said. "I'm just fighting not to have it be a double (bogey), and be a momentum killer. When that chip went in, it really propelled me to play the last 12 holes good."
Mickelson birdied the par-5 8th, then sank a 22-footer on the par-3 9th to reach 9 under. He dropped his 100-yard approach to No. 10 within 9 feet and made that putt, completing a stretch of eight birdies in 16 holes spanning the second and third rounds.
"A fun round," Mickelson said. "I got off to a good start, birdied the first hole and was able to kind of maintain the momentum."
Verplank is making only his fourth start of the year as he continues to cope with a sore left wrist, the result of a degenerative condition. He's somehow still managed to hit 34 of 42 fairways this week and is tied with Baddeley for second among the field in total putts (80).
"The pain obviously bothers everybody in different ways," he said, "but the thing that's bothered me with my golf has been the loss of stability."
Mickelson or Verplank, both over 40, could buck two trends on tour. A player in his 20s has won each of the last three weeks, and three events this year have had first-time winners.
Leading third round scores from the U.S. PGA Tour's Houston Open on Saturday (par-72; U.S. unless noted):
Phil Mickelson 70 70 63
Scott Verplank 73 65 65 204 Aaron Baddeley (Australia) 73 65 66
Chris Kirk 66 69 69 205 David Hearn (Canada) 69 70 66
Anthony Kim 72 64 69 206 Steve Stricker 67 72 67 207 Nate Smith 69 72 66
Hunter Mahan 70 71 66
Robert Allenby (Australia) 68 72 67
Padraig Harrington (Ireland) 68 69 70 208 Ben Curtis 70 70 68
J.J. Henry 73 70 65
Vaughn Taylor 68 71 69
Michael Putnam 70 69 69 209 Brandt Jobe 69 72 68
Matt Kuchar 72 70 67
Zack Miller 68 74 67
Greg Chalmers (Australia) 70 73 66
Nathan Green (Australia) 67 73 69
Ben Martin 73 66 70
Tim Petrovic 70 68 71
Jimmy Walker 63 74 72 210 Alex Cejka (Germany) 71 70 69
Ross Fisher (Britain) 71 70 69
Brian Davis (Britain) 71 72 67
Gary Woodland 71 70 69
David Mathis 70 70 70
Cameron Beckman 69 74 67
Webb Simpson 72 72 66
Cameron Tringale 74 70 66
John Rollins 67 71 72
Josh Teater 65 72 73