Pádraig Harrington closed his third round with three straight bogeys to finish four shots off the lead on nine under at the Shell Houston Open in Texas.
Defending Masters champion Phil Mickelson matched the course record with a sizzling 63 to move into a share of the lead with fellow American Scott Verplank on 13 under..
Mickelson showed he is in fine form ahead of the trip to Augusta by stringing together a nine-birdie round at the Redstone Golf Club.
Harrington had put himself in a strong position with six birdies and just one bogey over his opening 15 holes to move to 12 under.
His round started to unravel at the par-three 16th when his tee shot landed in rough to the right of the green. With a bunker and little room to play with on the green the Dubliner decided to play a rebound shot off the grandstand, only to see it come up short of the putting service.
He got down in two for a bogey and found sand with his approach to the 17th before taking three to get down.
Harrington drove in to the water on the 18th and after dropping on the far side of the lake did well to make a bogey five as he carded a 70.
After starting with back-to-back two-under-par 70s, Mickelson predicted he would need to “go low” in his third round to move into contention, and no-one has gone lower on this tournament course.
Adam Scott and Johnson Wagner both carded 63s in 2008, and Jimmy Walker matched that score on Thursday.
Mickelson was happy to reflect on a great day on the course, fuelling his confidence for the coming challenges.
“It doesn’t hurt,” said the 40-year-old. “I knew that I was close game-wise but I hadn’t been putting together the score. To get a good round like this means a lot.
“Also to have the challenge of tomorrow, to be in contention, to be in the final group, have an opportunity to win, I really enjoy that opportunity, that challenge, and I think it’s good for me to be in that position heading into next week, too.”
Verplank, who began the week by shooting a 73, today went round in his second straight 65.
Australian Aaron Baddeley and another US player, Steve Kirk, were one shot behind after their respective third rounds of 66 and 69.
Canada’s David Hearn (66) and former US Ryder Cup star Anthony Kim (69) will be within striking distance heading into the final round, after reaching 11 under.
Steve Stricker held seventh place on 10 under by himself, ahead of a four-man tie on nine under that includes Harrington, Nate Smith, Hunter Mahan, Robert Allenby.
World number two Lee Westwood signed for a disappointing two-over 74, ending his hopes of the top-two finish which would have taken him back to number one ahead of the Masters.
Westwood stands 11 shots off the pace, but his fellow Englishmen Ross Fisher and Brian Davis were just seven behind the leaders after their respective rounds of 69 and 67.
