GAINESVILLE, Va. - Chris DiMarco felt every bone in his body shaking as he stood over a 15-foot birdie putt late Sunday afternoon, captain Jack Nicklaus sitting with the American team beyond the hole and the Presidents Cup hanging in the balance.

Two people brought inspiration.

An hour earlier, the gigantic TV screen behind the 12th hole showed Fred Couples making a 20-foot birdie on the 18th hole for a stunning victory over Vijay Singh that essentially assured the Americans a tie.

And there was Nicklaus.

"That's what our whole goal was as a team this week, to win for him," DiMarco said. "We wanted this bad. We wanted this for Mr. Nicklaus. And it's nice to give him that."

Arms raised, his face awash in sheer joy over the biggest putt of his life, DiMarco charged toward the cup and then into the arms of the captain as the Americans won the Presidents Cup, sending Nicklaus into retirement as a winner with an 18.5-15.5 victory.

Only three matches reached the 18th hole Sunday - the dramatic birdie for Couples, a 4-foot birdie by Phil Mickelson to square his match with Angel Cabrera, and DiMarco's winning putt over Stuart Appleby.

Nicklaus already said farewell to the majors this year at an emotional British Open. He doubts he'll be a Presidents Cup captain again, wanting someone else to get a chance, so this likely was his last time in the spotlight, and his last chance to get a victory in this event.

"It feels a lot better to have a win, there's no question about that," said Nicklaus, whose team had lost badly in Australia in 1998, and tied in South Africa two years ago. "As far as being something special, I may never captain another team, I may never play another round of golf, and if I end my career this way, it's a pretty good way to end it."

Nicklaus put Mickelson and DiMarco in the final two matches, and they came through in the clutch.

Mickelson thought he had earned the clinching point when he stuffed a wedge into 4 feet and made birdie on the 18th hole to square his match with Cabrera. But under new rules this year, every match had to go extra holes until one team had enough points to claim the cup. Someone apparently forgot to tell Mickelson.

With the Americans already at 17 points, Mickelson pounded his fist when the putt fell, removed his cap to shake hands and was ready to start the celebration when European tour rules official Andy McFee broke the news - the match wasn't over. Mickelson looked on with utter shock, and headed to the first tee.

"I thought we had won, because I'm an idiot and didn't read the rules of the game," Mickelson said as his teammates laughed with him. Mickelson never had to finish the extra hole.

As he studied his chip, he heard a massive roar behind him from the 18th green that told him all he needed to know.