Atlanta - Seven years after being fierce rivals at the Walker Cup, Billy Horschel and Rory McIlroy will play together in Saturday's third round of the Tour Championship where playoff honours and a staggering $10 million bonus are on the line.
American Horschel, the game's hottest player over the past three weeks, holds a two-shot lead in the PGA Tour's season-ending event but Northern Irishman McIlroy, the world number one, is close behind in a tie for second.
While Horschel is bidding for a second consecutive triumph on the U.S. circuit and the third of his career, McIlroy is chasing his fifth win worldwide this year to cap a brilliant 2014 campaign highlighted by two major victories.
Both players have already achieved a great deal in professional golf and have become good friends since they locked horns as amateurs in the 2007 Walker Cup at Royal County Down in Northern Ireland.
Horschel upset McIlroy with his "obnoxious" antics at Country Down where he beat McIlroy one-up in the singles and then 2&1 in the foursomes in partnership with Rickie Fowler.
Though McIlroy gained a measure of satisfaction with a 4&2 victory over Horschel in the last-day singles, the United States went on to defeat Britain & Ireland by a point.
"Everyone knows about the Walker Cup between us," Horschel, 27, told reporters after firing a four-under-par 66 on a steamy Friday at East Lake Golf Club in the fourth and final FedExCup playoff event. "But he's a good buddy.
"If I happen to come out on top and we're battling out on these next two rounds, that would mean a lot. The guy won three straight events in a row and two of them happened to be majors. That's pretty impressive.
"When you're able to go toe-to-toe with the number one ranked player in the world and you're able to come out on top, that would give anybody a lot of confidence."
McIlroy, who told Golf Digest magazine in 2008 that Horschel had been "so loud and so obnoxious" at the Walker Cup, fired a best-of-the-day 65 at East Lake on Friday to surge into contention for his fourth PGA Tour victory of the season.
In a storming late summer run, the 25-year-old clinched the British Open, the WGC-Bridgestone Invitational and the PGA Championship in consecutive starts to embellish his status as the game's best player.
"I'm going into this weekend I feel with nothing to lose," said McIlroy, who has never previously won FedExCup playoff honours and had targeted that as a specific goal this week at East Lake.
"I'm the one that's got the two majors this year. I'm the one that's had the great season. Those other guys (in Tour Championship contention) are trying to cap off a great season for themselves.
"I just want to finish my season off the way I feel like I should and the way I feel like it deserves to be finished off."
Horschel, however, will be difficult to beat if he maintains his red-hot form to close out the 2013-14 PGA Tour season.
The American rose to second in the FedExCup points list after tying for second at the Deutsche Bank Championship two weeks ago and then winning the BMW Championship on Sunday.
"It gives me a lot of confidence knowing that when I'm in that lead I can play my game and I can still come out on top," Horschel said, referring to his victory at the BMW where he was three ahead going into the final round.
"I know I can close out a tournament if I can do my thing and focus on what I'm doing, not let someone else or some other guys affect how I'm going about my game plan."