"Welcome to the Ryder Cup," a smiling Graeme McDowell told his girlfriend, Kristin Stape, as they walked off the 18th green on Friday morning, after he and Rory McIlroy had beaten Jim Furyk and Brandt Snedeker by the narrowest of margins in the opening match of the tournament.

By the end of the day Stape, an interior decorator from Florida, had seen both sides of the Ryder Cup as her Northern Irishman and his compatriot crumbled in their afternoon fourball match against Phil Mickelson and Keegan Bradley. Behind all the way, they gradually subsided to defeat at the 17th hole, with McDowell's sudden slump in form a particular cause for concern.

The United States pair had come into the second session on the back of an outstanding 4&3 win over Luke Donald and Sergio García, who had been expected to do rather better as José María Olazábal sent out a set of pairings clearly designed to establish an early lead in the three-day competition. Unlike McIlroy and McDowell, Mickelson and his partner carried their good form through lunch, with Bradley ending up as the undisputed player of the day.

Perhaps the Northern Irishmen felt that in the four hours and five minutes of the first match they had already lived through an entire Ryder Cup, with its endless fluctuations, a smattering of shots of celestial brilliance and a lively disagreement in a setting of great beauty.

The start had been subdued enough, at least until a US official belatedly arrived to hand out flags to the home fans lining the 1st tee but the match sprang to life on the par-three 2nd. Half a dozen geese were circling overhead and the low sunlight was glinting off the placid surface of Lake Kadijah when McIlroy sent his tee shot over the water, the ball coming to rest on the fringe of longer grass a few inches from a sprinkler head. Snedeker's tee shot then rolled to a halt on the putting surface, 40ft from the pin.

McIlroy asked the match referee for relief, suggesting that the ball was lying on grass affected by the sprinkler. The Americans disagreed, with Furyk at the forefront of the discussion. It took 10 minutes for a rules official to arrive, time enough for a voice in the gallery to offer McIlroy a suggestion: "Hit a better tee shot next time!" Furyk could be seen holding up his hands to the crowd, asking for restraint.

The official took barely a minute to announce his conclusion. Play it as it lies, he ordered and McDowell chipped carefully down to around 7ft from the hole, while Furyk placed his long putt to a similar distance. McIloy narrowly missed his short putt but Snedeker's dropped nicely, giving the USA an early advantage.

On the par-four 4th there came a moment that McIlroy is unlikely to better all weekend. Facing a difficult 60ft chip on to a down-sloping green, he feathered his wedge quite perfectly and watched as the ball rolled, rolled again, and rolled some more until it dropped into the cup with its last drop of energy. It was a regal touch from the world's No 1 golfer and it squared the match.

The sun had disappeared and a cold wind gusted as the Europeans took the lead on the 6th, thanks to McDowell's wonderful approach shot. Snedeker stroked in a 6ft putt to level the match at the 8th but at the next hole it was McDowell's turn to shine with a successful 15ft birdie putt, and Europe were leading again.

The Northern Irishmen accelerated out of the turn, winning the 10th – where Furyk demonstrated the best side of golfing etiquette by calling a foul on himself after the ball moved fractionally as the grounded his club behind it – and the 11th, despite excursions into the bunkers.

Three up with six to play, it looked as though the Europe pair might be on the way to an early lunch. But at the short 13th Furyk tapped home a five-footer to cut the lead and at the 15th Michael Jordan turned up, apparently bringing his mojo with him. Furyk hit a majestic drive to the throat of the putting surface and Snedeker put the ball to within 5ft, while McDowell's tee shot dropped into a lagoon. The former Chicago Bulls star gave Furyk an appreciate low-five and a butt-slap as they made their way to the 16th.

It seemed to work because Furyk raked a magnificent approach shot to within two and a half feet of the pin. The match was all square and so it remained as they arrived at the final hole, a 449-yard par-four.

"Oh no – that's in the chalets," a marshal groaned as Snedeker's drive faded into the walkways alongside the white hospitality units. Europe's effort might have followed had their drive not bounced back of a tree into the longer grass alongside the fairway. McIlroy was able to chip to 5ft and after Snedeker had missed from 20ft, a nerveless McDowell rolled his putt into the centre of the cup.

It had been a highly promising start to the weekend for the European duo and their team but their form cooled as the sun returned to warm the afternoon and they faced opponents who had needed to play only 15 holes in the morning. In Bradley they were facing a man who had virtually carried his partner during the foursomes and was to do so again as they raced to a three-hole lead. At that point the American pair had won seven holes in a row across both matches, four of them with Bradley's birdies.

The 26-year-old comes from Woodstock – not the festival one but a small town in Vermont where he learnt to ski well enough to become a top junior racer. But his father is a golf pro – currently in Jackson Hole, Wyoming, another ski resort – and his aunt is a former women's PGA champion. Once Bradley had made the decision to make golf his career, he moved fast. Last year he won the PGA Championship, becoming only the third man in history to win a major at his first attempt.

He gave much of the credit for that success to the encouragement of Mickelson, a frequent practice partner. Their ease with each other was evident as they preserved their advantage and held off the Northern Irishmen's attempts to force their way back into the match.

At the 578-yard 10th hole, Bradley set himself up for a eagle putt from 12ft but had to be content with his fifth birdie of the afternoon. One of the few flaws in his day came when he missed a 10-footer at the 14th, allowing McIlroy's birdie to reduce the deficit to two holes.

On Tuesday evening Bradley had described the first practice day at Medinah as "the most fun I've maybe ever had on a golf course – I kind of expect that to happen every day this week." On Friday, encouraged by his partner as he unleashed one outstanding shot after another, the 26-year-old's performance formed the spine of a team effort that left the USA well satisfied with their return from the opening exchanges.