The European side, the two-time defending champion and winner of four of the last five Ryder Cups, is ahead 5-3 at a soggy K Club. Rain came down several different times, but play was never halted.
Tiger Woods and Jim Furyk got the Americans on the board Friday morning with a fourball victory, but struggled late in their foursomes match. They lost the final two holes to give Sergio Garcia and Luke Donald a 2-up victory.
'I did struggle in probably the first six, seven holes in the morning,' admitted Woods. 'But I got it turned around and hit some really good shots, and this afternoon, I actually hit it pretty good.'
Not all of the news late in Friday's matches was bad for the Americans. Chad Campbell and Ryder Cup rookie Zach Johnson birdied the last three holes to earn a halve against Irishmen Padraig Harrington and Paul McGinley.
Friday's other foursomes match featured another close contest. David Toms and Stewart Cink birdied the 15th hole, then held on for pars as they halved their match against David Howell and Henrik Stenson, who came off the European bench Friday afternoon.
In the morning fourballs, the European side grabbed a 2 1/2 - 1 1/2 lead. Woods and Furyk toppled Harrington and Montgomerie, 1-up.
Cink and rookie J.J. Henry fought back to earn a half against Paul Casey and Robert Karlsson, while Garcia and fellow countryman Jose Maria Olazabal dispatched Toms and Brett Wetterich, 3 and 2.
In the final fourball match, Darren Clarke, competing in the Ryder Cup a little over a month after losing his wife Heather to cancer, teamed with good friend Westwood to best Mickelson and DiMarco, 1-up.
'I'm obviously very, very pleased that I got a point, that Lee and I have got a point for the team,' said Clarke. 'It was always going to be a big morning for me. I said I'll get myself through this week, and so far I think I've done that pretty well.'
As difficult as it is to be trailing, the American team can take solace in one thing. At this point in 2004, at home, the U.S. trailed 6 1/2 - 1 1/2 en route to the worst loss in history, an 18 1/2 - 9 1/2 drubbing.
'Obviously there were a lot of tight matches,' said American captain Tom Lehman. 'We didn't make a lot of putts. That would be the one thing that I would say was the difference in the day between the two teams. I felt like our team hit a lot of good putts, but didn't make many. The European team definitely made the putts they needed to when they had to.'
In what turned out to be the final match on the course, Montgomerie and Westwood took the lead with a birdie at the 13th. Mickelson and DiMarco only needed par at 14 to square the match, but took a 1-up lead with a birdie at the par-5 16th.
DiMarco had the honor on the tee at the difficult 17th and drove well right of the fairway. Mickelson hit a spectacular approach that landed on the green and the two posted a two-putt par that halved the hole.
At the par-5 last, DiMarco hit the team's second into a greenside bunker. Montgomerie ripped a 3-wood on to the front portion of the putting surface. Westwood ran his long eagle putt 6 feet past the hole, while Mickelson blasted out 10 feet short of the stick.
DiMarco missed his birdie try, but Montgomerie did not.
Mickelson and DiMarco weren't the only highly-tauted American team that played poorly in foursomes. Woods and Furyk, the only U.S. winners in the morning against Montgomerie and Harrington, double-bogeyed the first when Furyk's drive landed against a tree and never took the lead from there.
They were 2-down when Donald drained a birdie putt at the 12th, but Woods and Furyk, ranked first and third in the world, respectively, clawed back. Furyk holed a long birdie putt at 13, then Woods knocked the team's tee ball stiff at the par-3 14th. The Europeans had a birdie look, but missed and conceded the Americans birdie to tie the match.
At the par-4 17th, Furyk missed a 10-foot birdie putt and lost the hole since Garcia hit the team's approach inside 3 feet. The Europeans were armed with a 1-up lead heading to the final tee.
Woods drove into the fairway, but Furyk hit a hybrid-club left into the water. That allowed the Europeans to win the 18th with a par and walk off with a 2-up victory.
'I hit the ball way on the toe and made a poor swing from over the top,' said Furyk, referring to his errant shot at 18. 'So I have no excuse there. I made a bad swing.'
In the opening foursomes match, the Americans had plenty of chances for birdies, but could not get the flat stick working. That is, until late in the match.
Campbell and Johnson were 2-down with three holes to play and at the par-5 16th, Johnson reached the green in two and Campbell lagged it down to 2 feet. Johnson tapped in the birdie putt to cut the deficit to 1-down.
Johnson rolled in a 25-foot birdie putt at the 17th, but McGinley followed him in the hole from 9 feet to halve the hole. At the 18th, Harrington drove into the right rough and McGinley had to lay up with the team's second. Johnson put the Americans on in two and it came down to short games.
Harrington put the team's third over the green, but McGinley chipped to concession range. The Irish duo made par, but Campbell ran the eagle putt 4 feet past the hole. Johnson calmly stroked home the birdie to win the hole and halve the match.
'It's obviously disappointing. The boys finished well,' acknowledged Harrington. 'They finished birdie, birdie, birdie, which is what was asked. They certainly deserved a halve, even though we feel a little bit disappointed with the halve.'
Cink and Toms birdied the second to win the hole, but the Europeans birdied three to square the match. Europe remained ahead through most of the match and when Howell's drive found water at 15, the match was even.
Both teams had birdie looks at 18. Toms' 25-footer lipped out of the hole, but Howell narrowly missed his birdie putt to end the match in a halve.