In the opening match Tiger Woods hit his tee shot on the first into the water and continued to struggle early, only to be propped up by partner Jim Furyk with birdies on the 1st and 9th holes.
Woods regained composure and sent the US first pair to 3-up with consecutive birdies on 11 and 12, only for Europe's Colin Montgomerie and Padraig Harrington to reduce the margin, scoring birdies on 14 and 16 respectively.
However the Americans held on, winning the match 1-up after 18 holes and drawing first blood for the USA in the trans-Atlantic matchplay tournament.
In the second match, Briton Paul Casey and Ryder Cup rookie Robert Karlsson from Sweden were 3-up on Stewart Cink and debutant J.J. Henry after 10 holes, but Henry birdied the 11th, 12th and 15th to swing the match in the Americans' favour.
The match ended all-square giving each side half a point when Casey birdied the 16th and the last two holes were halved.
Sergio Garcia and Jose Maria Olazabal teamed up for Europe in the third match against David Toms and Brett Wetterich, with the two Spaniards taking the lead on the first hole and never looking back.
Garcia birdied the 15th to go 3-up, and then sealed the match with his sixth birdie of the round on the 16th to see Europe win the match 4 and 2.
The final fourballs match on day one saw European wildcards Darren Clarke and Lee Westwood take on Phil Mickelson and Chris DiMarco with the Europeans going 1-up twice during the round only for the US to fight back to all-square.
Clarke, whose wife Heather died last month after a battle with cancer, birdied the first hole to a rousing ovation from the gallery at the K Club.
The final group played the last three holes in a steady downpour of rain, with another Clarke birdie on the 16th sending Europe 1-up in the match with two holes to play.
Clarke and Westwood held on for a handy 1-up win over the more fancied American pairing, giving an early lead to the Europe team.