A tremendous fairway shot by American Jonathan Moore to set up an eagle 3 ended a thrilling fightback by Great Britain & Ireland and gave the US a 12.5-11.5 win that retained the Walker Cup they won two years ago in Chicago by the same score.

Facing what looked a near mission impossible after a foursomes whitewash that left GB&I four points adrift, wins by Rory McIlroy, Rhys Davies, Lloyd Saltman and Jonathan Caldwell and a fighting half by Daniel Willett against the top US player Colt Knost, gave hope of a great comeback.

"I'm gutted for the team," said Colin Dalgleish, the GB&I captain. "This morning cost us big time. To lose the foursomes 4-0 was an absolute killer. Coming back from four points down was a big shout, but we made a good run at it."

GB&I needed 6.5 points out of eight in the final session for victory; however, just when the dream seemed within touching distance, Moore, 22, the 2006 NCAA champion who will turn professional today, produced that wonder stroke, an exquisite four iron of 252 yards.

"I never dreamed it would get that close. It came off perfectly," he said. "This was the opportunity of a lifetime and I'm just really thankful."

After Welshman Nigel Edwards was conceded his birdie at the 550-yard par-5 hole that had been the scene of many dramatic moments over the weekend, Moore stepped up to hole from four feet to take the US to the 12.5-point mark that was unassailable.

Moore added: "I told myself that this is why I practised this length of putt over and over again since I was 12. Then I tried to go into my normal putting routine."

It was a spine-tingling finish that seemed unlikely after the 4-0 drubbing in the morning to give the US a 10-6 advantage.

"I've never seen such naked courage on a golf course,"

said Peter McEvoy, the former GB&I captain who has been a key figure on the modern-era revival of GB&I in a competition that was previously dubbed the Walkover Cup.

During lunch the GB&I team raised spirits by talking about famous team golf singles fightbacks. These included GB&I's performance in the Walker Cup at Nairn in 1999 when they won the closing session 7-1 for a 15-9 win, and the European Ryder Cup team at The Belfry in 2002 when they won the closing session 7.5-4.5 to win by a point.

McIlroy said: "On both occasions it was vital to get blue up on the board quickly and that was what we had to do."

The 18-year-old who turns professional today had contributed just a half point in three outings and he was up against 20-year-old Billy Horschell who had three points out of three.

As huge cheers rang out throughout the course in the scenic setting in the shadow of the mountains of Mourne, McIlroy saved his best performance until last and set the ball rolling with a 4&2 win that headed a run of blue in the three matches behind.

Welshman Davies followed suit, closing with a birdie 3 at the 16th to end teenager Rickie Fowler's perfect record by 3&2, covering his last six holes in a sparkling four under par.

Scotland's Saltman struck next. Dropped for the morning foursomes after dismal showings in the first two sessions, he was one under par for the 17 holes that it took him to despatch the 35-year-old American Trip Kuehne.

What a shame for GB&I it took these three players, the most experienced in the outfit, until the final session to find form. Ultimately, it was the fact that among them the top order managed just 1.5 points out of eight in the first three sessions that was the downfall.

Over that spell the trio had the worst figures of the team, amounting to an estimated aggregate of 37 over par. The other seven combined to just 13 over, gritty showings by England's Jamie Moul and David Horsey, in particular, keeping GB&I in with a shout.

In comparison, the US top three of Horschell, Fowler and Knost amassed 8.5 points out of nine in that same period.

Saltman said: "I was disappointed with myself yesterday, but the team did well in the end. I worked with my coach Colin Brooks on the range this morning and came out determined."

After Saltman's win that came from a curling right to left five-footer - he holed putts of eight and 15 feet at the previous two holes for a win and a half respectively - Willett gutsily holed from 25 feet for a birdie at the last that ultimately secured a half against Knost.

Horsey won the final match on the course against Webb Simpson by one hole to give him the best personal GB&I figures of three points out of four.