Kim was in inspirational form at the Ryder Cup at Valhalla

Ryder Cup star Anthony Kim continued his superb form to take a four-stroke lead after the first round of the elite 30-man Tour Championship in Atlanta.

The 23-year-old American, who thrashed Sergio Garcia in the opening Ryder Cup singles on Sunday, shot four birdies in five holes on his way to a round of 64.

Ryder Cup team-mate Phil Mickelson is tied in second place alongside South Africans Ernie Els and Trevor Immelman.

Garcia, the only European team member playing, shot a level-par 70.

Eight other members of the triumphant United States team received a rapturous reception from the galleries at what is the final tournament of the PGA Tour FedEx Cup play-off series and the last of the regular season.

It was playing very tough and I'll take anything under par Phil Mickelson

But it was Kim who stole the show with a stunning six-under-par display on a day when only five players broke even as the renovated greens proved lightning-fast in breezy conditions.

"I'm just trying to enjoy the moment," he said. "This Ryder Cup hangover doesn't feel as bad as a college hangover.

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

"I figured something out on the putting green. 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 everything in my game was clicking pretty well out there."

Mickelson, champion in 2000, got to four under before slipping back with bogeys on 16 and at the last.

"It was playing very tough and I'll take anything under par. I'm pleased with two under," he said.

Els was satisfied with his 68, despite bogeying the par-three 18th.

"I'm pretty happy with it," the world number six said of a round that included five birdies and three bogeys. "It's a little windy out there and the greens are firm."

Vijay Singh, who has all but secured the season-long points race for the FedExCup, bogeyed four of the first four holes before ending the day nine strokes off the lead with a 73.

After winning the first two of the four play-off events, the Fijian simply needs to complete Sunday's final round to lift the trophy and pocket $9m in cash with $1m deferred.