Atlanta - Henrik Stenson upstaged his rivals on the opening day of the $8.25 million Tour Championship on Thursday, firing a seven-under-par 63 to snatch a two-shot lead over England's Paul Casey.
The pre-tournament hype had focused on the prospect of a battle between golf's "New Big Three" of world number one Jason Day, reigning Masters & US Open champion Jordan Spieth and four-time Major-winner Rory McIlroy.
But instead it was Swedish veteran Stenson who seized his chance to shine at the USPGA Tour's season finale, opening with consecutive birdies at the first three holes before a further birdie and an eagle left him six under at the turn.
Another birdie on the 10th raised the tantalising prospect of Stenson breaking 60, and that rare feat looked within his grasp after he drained a six-foot birdie putt at the 12th to go eight under with six to play.
However Stenson was unable to pick up any more shots and bogeyed the 17th to fall back to seven under - two clear of Casey who shot 65.
"At that stage I was just trying to get up and hit the fairways, give yourself chances, because they're tricky holes," Stenson said of the finishing holes on the par-70 East Lake course. "It's all about just keeping it going.
"I didn't quite hit it as good the last five or six holes as I did for the first 12, but if I could have that (two-stroke) spread for the next three days, I think I'll take it," he added.
McIlroy meanwhile was three off the lead after a four-under-par 66 comprising six birdies and two bogeys. Zach Johnson was level with McIlroy on four under.
Spieth was in a group of six players five shots off the lead at two under after carding a 68.
Spieth never managed to get his putter going on a frustrating front nine, sinking only one birdie to be one under at the turn.
The Texan holed a 10-footer to pick up a birdie on the 12th but his momentum was undone by a bogey on the next hole.
He improved his score with a birdie on the 15th, coolly dropping a 13-foot putt for birdie.
"Today was definitely an off day and I was able to get in at two-under," Spieth said. "This is a round that earlier in the playoffs was a four-over round. So I really improved the consistency, even on my misses. And that gives me confidence."
World number one Day was a shot behind Spieth after a round which promised so much finished in an ultimately disappointing 69.
The in-form Aussie had looked to be the player to beat after notching birdies on the first three holes of the day.
But a disastrous triple-bogey seven on the par-four fifth negated his good early work and though he picked up a birdie on the eighth, the opportunity of a low score remained elusive.
Day and his rivals are all chasing the $10 million bonus on offer to the winner of the FedEx Cup playoff points race.
Five other players, including Rickie Fowler, were grouped with Day at 69.
Stenson, the 2013 playoff champion, is trying to join Tiger Woods as the only players to win the FedEx Cup twice.
He liked his chances of keeping things going at East Lake.
"It's definitely a ball-striking golf course," Stenson said. "And when I'm hitting it nicely, it's always going to work for me. It's always going to suit me."
Earlier on Thursday, South Africa's Louis Oosthuizen limped out after suffering a hamstring injury, placing a question mark against his fitness for next month's President's Cup.
The 2010 British Open champion was five-over through 13 holes when he withdrew, saying the muscle injury had impeded his ability to swing properly.First-round scores on Thursday in the $8.25 million US PGA Tour Championship, final event in the FedEx Cup playoff series (USA unless noted, par 70):
63 - Henrik Stenson (SWE)
65 - Paul Casey (ENG)
66 - Rory McIlroy (NIR), Zach Johnson
68 - Kevin Na, Brooks Koepka, Brandt Snedeker, Steven Bowditch (AUS), J.B. Holmes, Jordan Spieth
69 - Danny Lee (NZL), Hideki Matsuyama (JPN), Daniel Berger, Dustin Johnson, Rickie Fowler, Jason Day (AUS)
70 - Justin Rose (ENG), Bubba Watson
71 - Harris English, Matt Kuchar
72 - Bill Haas, Patrick Reed
73 - Bae Sang-Moon (KOR), Jimmy Walker, Charley Hoffman
74 - Scott Piercy
75 - Robert Streb
76 - Kevin Kisner
WD - Louis Oosthuizen (RSA)
DNS - Jim Furyk