Mike Weir fired a stunning 61 to take a three-shot lead after the first round of the Deutsche Bank Championship.
Canadian Weir soared to 10 under to head Vijay Singh, John Merrick and Briny Baird and Heath Slocum in Boston.
US Ryder Cup debutant Ben Curtis and Eric Axley were six under, with Ernie Els in a group five under.
Swede Carl Pettersson and Sergio Garcia were four under, while European Ryder Cup hopefuls Paul Casey and Ian Poulter were -3 and -1 respectively.
Casey, 31, failed to qualify for one of the top 10 automatic spots on the European team and is banking on one of captain Nick Faldo's two wildcards, to be announced after the Johnnie Walker Championship in Scotland on Sunday.
"There is absolutely nothing I can do in terms of qualification," said the Englishman after carding 68.
"I can't qualify in the Euro points list and I can't qualify in the world rankings list so, as far as that's concerned, I am as relaxed as they come.
"But I have been playing some very solid golf recently. My focus is this week, trying to give myself the opportunity to win (the overall prize of) $10m (£5.5m) and try and win a golf tournament."
"I find it mind blowing you can win $10m for getting hot for two weeks. That freaks me out - it's nuts"
Casey and Poulter are vying with Northern Ireland's Darren Clarke and Scotland's Colin Montgomerie for a wildcard.
When Faldo's picks are announced at about 1900 BST on Sunday, Casey is likely to be out on the TPC Boston course playing his third round.
"I don't know what time we will tee off on Sunday but I hope to be in the last couple of groups, maybe going down the fourth fairway or something like that," added Casey.
"My communication with Nick has been pretty good so I am sure he will tell me when he's made the decision. It could be distracting but I think I always want to know.
"I'm a guy who looks at scoreboards. I like to know what to do, what I've got to do and I don't think finding out will affect my game."
Only the top 30 players on the FedEx Cup points standings after next week's BMW Championship qualify for the following event, the season-ending Tour Championship.
Weir, 36, took only 21 putts in his course record-equalling round which included 10 birdies.
"I wish I could bottle that," he said. "It was one of those rare days with my putter I hadn't had in a while. Everything seemed to look easier."
The two-time Open and USPGA champion Padraig Harrington came into the Deutsche Bank Championship 23rd in the standings, but carded a three-over-par 74 to finish in last place and likely to miss the cut.
The Irishman will drop a long way outside the top 30 on the rankings, and will need a stunning performance next week to climb back for the Tour Championship, which will also be without the injured world number one Tiger Woods.
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"It amazes me that Padraig could have an average week this week and next week and not be in the Tour Championship," Poulter said.
"He's won two majors, for Christ's sake. How can you have a double major winner that very year not make the Tour Championship?
"That's complete and utter nonsense. Do you think Coca-Cola (sponsor of the Tour Championship) will be happy if a double major winner is not there?"
"I find it mind blowing you can win $10m for getting hot for two weeks. That freaks me out - it's nuts."
Eight players have already qualified by right for the US Ryder Cup team but four further spots will be awarded by skipper Paul Azinger on 2 September.
Among those in the reckoning, DJ Trahan shot 67 for four under, Steve Stricker and Rocco Mediate were two under, Hunter Mahan was one under and Woody Austin was one over.
America's world number two Phil Mickelson shot 69 for two under.
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