Padraig Harrington and Paul McGinley halved with Chad Campbell and Zach Johnson in the foursomes.
The Irish pair three-putted the first, Harrington missing from three feet, but made amends with a birdie two holes later when McGinley hit his tee shot to nine feet and went ahead when their opponents bogeyed the sixth.
Campbell and Johnson, the latter making his debut, squared when the two Dubliners bogeyed the ninth, but they dropped a shot themselves on the 11th and Johnson's missed five-footer at the 13th kept them one down.
Both teams bogeyed the next and Harrington's seven-foot par putt won the 15th after the Americans, going through a really sticky patch, three-putted.
Johnson did his confidence a power of good by finding the green in two at the long 16th and by making a 12-footer on the next, but while the first of those holes was won the second was only halved as McGinley followed him in brilliantly from 10 feet.
One up with one to play Harrington found the rough off the tee and then pitched over the green. McGinley saved their par, but the Americans two-putted for their third successive birdie and a half.
