Golf: American Anthony Kim enjoyed a world-class Ryder Cup celebration, but he knuckled down to open a four-stroke lead after opening round at the lucrative Tour Championship.

"It took me a couple of days to get over that celebration we had on Sunday night, so I wasn't expecting too much," Kim said after recovering from a bogey at the first hole, subsequently picking up eight birdies in a spectacular six-under-par 64 in demanding, breezy conditions at East Lake.

Fellow American Phil Mickelson and South Africans Ernie Els and Trevor Immelman were a distant equal second with two-under 68s, with Korean KJ Choi, on 69, the only other player to break par.

Fiji's Vijay Singh, who only has to complete the 72 holes to clinch a $10 million bonus as the FedEx Cup champion, struggled to a 73.

He made a terrible start, with four bogeys in eight holes, before steadying the ship somewhat on the back nine.

Kim, who posted his maiden PGA Tour victory in Charlotte in May, is coming off a spectacular Ryder Cup, where he recorded two wins, one loss and one half.

His performance in his singles match on Sunday was simply magnificent, as he gave Sergio Garcia a 5&4 hiding in the opening match to set the tone as the Americans charged to victory.

Kim, 23, used to be a big party animal so it is no surprise to hear that Sunday's night's celebrations dragged well into Monday.

"This Ryder Cup hangover doesn't feel as bad as a college hangover," he said. "I'm over it now and just focusing on this tournament.

"The course is playing a lot tougher than I had heard about. I thought the winning score was going to be around 20 under again, and I don't think it's going to get there."

He was referring to the 23-under total Tiger Woods shot to win last year, when the greens were very soft. But they have been replanted since, and are very firm and fast this year.

"I figured something out on the putting green this morning," Kim continued. "It was the most basic thing, to keep your eye on the ball. Now I've got that under control, I'm going to try to make some more putts.

"Almost every thing in my game was clicking pretty well out there."

Mickelson, meanwhile, charged to four under at the turn, only to bogey the next two holes. He fought back with two birdies, only to fritter away two more shots over the final three holes.

"It was playing very tough today and I'll take anything under par," said Mickelson. "I made a few bogeys on the back but I'm pleased with two under."

Mickelson is coming off another disappointing Ryder Cup. He recorded one win, two defeats and two halves, bringing his career record to 10-14-6.

Masters champion Immelman had a nice round, making only two bogeys in the testing breeze.

"Any time you can shoot par or better on this course you've played real well," said Immelman.

"So it was nice for me to go out today and hit some solid shots and hole a few nice putts. My driver was a little wayward on the back nine but I stepped up and hit a good one on 17, so that was a nice way to finish off."

Els bogeyed the last, but after making four birdies on the back nine, could hardly complain.

"I'm pretty happy with it," he said. "A little windy out there, the greens are firm and the 18th hole is never the easiest to finish on.

"I played pretty well, kept the ball in play most of the day and didn't do anything stupid, and I putted quite nicely for a change."

Garcia, the only European Ryder Cup member in action, recovered from a poor start to shoot 70.

He lost his ball after a wayward drive at the par-four fifth, running up a double bogey, but battled back nicely to finish the day equal sixth.

Collated first round scores

(USA unless stated, par 70):

64 Anthony Kim

68 Phil Mickelson, Trevor Immelman (Rsa), Ernie Els (Rsa)

69 KJ Choi (Kor)

70 Sergio Garcia (Spa), Mike Weir (Can)

71 Ben Curtis, Kevin Sutherland, Bubba Watson, D.J. Trahan

72 Chad Campbell, Jim Furyk, Billy Mayfair, Camilo Villegas (Col), Stuart Appleby (Aus)

73 Dudley Hart, Vijay Singh (Fij), Justin Leonard, Andres Romero (Arg)

74 Steve Stricker, Hunter Mahan, Briny Baird

75 Robert Allenby (Aus), Ryuji Imada (Jpn), Stewart Cink

76 Kenny Perry, Carl Pettersson (Swe)

77 Ken Duke

78 Tim Clark (Rsa)