Determined to get off to a better start, Weir birdied the first four holes and one-putted his final nine greens in the Deutsche Bank Championship to tie the course record at TPC Boston with a 10-under 61, the lowest round of his PGA Tour career.
Weir had a three-shot lead over a group of four players that included Vijay Singh, whose victory last week at The Barclays put him atop the standings in the PGA Tour Playoffs for the FedEx Cup.
Singh previously had the TPC Boston course record to himself, a 61 in the third round two years ago. And the Fijian set the tone for a day of low scores when he ran off five birdies in a six-hole stretch for a 64.
It took Weir only 10 holes to catch him.
"There was no indication on the putting green when I was warming up that was going to tell me it was going to be like that," Weir said. "It just felt normal. Just one of those days where I made about a 15-footer on the first hole, another on the second hole. ... I just kind of built on that momentum.
"I just tried to keep the pedal down, because I knew the scores were pretty low."
John Merrick, Heath Slocum and Briny Baird joined Singh at 64, while Ben Curtis had a 65. Ernie Els and Jim Furyk were in a large group another stroke back. More than half of the 115-man field shot in the 60s, and only 23 players failed to break par.
Even so, Weir never saw a 61 coming.
In his 20 previous stroke-play events this year, he had shot in the 60s only one time, at the Canadian Open.
"It's been kind of my goal the last month or so to get off to better starts in tournaments," he said. "It seems like I've been having to come from behind. I've just put it in my to try to get off to a better start. Obviously, this was way exceeding my expectations."
Only three of his birdie putts were inside 10 feet, including a 5-footer on the 18th that gave him his career low on tour, one shot better than a 62 in the first round at Doral seven years ago.
The only noticeable difference was a clean-shaven face.
Weir had been on vacation when he grew a light beard, and he kept it for the first round of the playoffs last week at The Barclays, where he tied for seventh. He also stars in a PGA Tour commercial with Wayne Gretzky, who urges Weir to grow a playoff beard as if these were the Stanley Cup playoffs.
But when his wife and daughters (ages 10 and 8) arrived on Tuesday and his girls wouldn't kiss him, Weir gave each a razor and let them start stripping away the beard.
The playoff atmosphere was not as great as last year, perhaps because Tiger Woods isn't around to make his playoff debut, and there wasn't the star power centered on one group as there was last year when Woods, Singh and Phil Mickelson played the first two rounds.
Mickelson, the defending champion, suffered through a familiar malaise. He hit the ball fine, but 31 putts kept in the middle of the pack at a 69.