The afternoon fourballs were finely poised at the midway stage as Europe sought to narrow their Ryder Cup deficit.
Davis Love's American side took the morning foursomes 3-1 to open up a healthy 8-4 lead.
Tiger Woods and Steve Stricker were the only United States pair trailing as the afternoon fourballs took shape on a Medinah course where the former won both the 1999 and 2006 USPGA Championships.
They lost the first two holes to Luke Donald and Sergio Garcia, both seeking their first points of the week, and were three down after Donald's birdie at the short eighth.
Ahead of them, however, Bubba Watson and Webb Simpson led Justin Rose and Francesco Molinari by three with eight to play and behind them World Number One Rory McIlroy and Ian Poulter - Europe's best performer so far - were two down to Jason Dufner and Zach Johnson after seven.
In the other game Nicolas Colsaerts, who in two games has already experienced the wonderful highs and awful lows of Ryder Cup competition, and Paul Lawrie were on level terms against Dustin Johnson and Matt Kuchar as they started for home.
It was the home side - most notably Keegan Bradley and Phil Mickelson - who had dominated proceedings so far.
Rose and Poulter, improving his phenomenal record in the event to ten wins and only three losses, were the only pre-lunch European winners.
They beat Watson and Simpson, respectively the Masters Tournament and US Open Champions, on the last in a game which began so dramatically with both Poulter and Watson encouraging the crowd to make whatever noise they liked as they teed off.
For pure theatre golf has never seen anything like this new trend, started by the eccentric Watson when he entered the fray yesterday afternoon.
But as they slugged it out over 18 holes Mickelson and Bradley needed only 12 to beat hometown boy Donald and Lee Westwood and register a third straight win together.
Their 7 and 6 margin over the World Numbers Three and Four equalled the competition's record winning margin for either fourballs or foursomes.
Then, after Poulter and Rose had done their stuff, Belgian Colsaerts discovered that 18 hours in The Ryder Cup is a long time - time enough to go from ecstasy to agony.
The 29 year old debutant notched eight birdies and an eagle as he gained the notable scalps of Woods and Stricker in his first game.
But on his return his tee shot into the water on the 17th, the hole where he had so dramatically matched Woods's birdie yesterday, led to a 2 and 1 one defeat for him and Garcia.
McIlroy and Graeme McDowell looked as if they might make up for that when they birdied the 16th to be only one down to Jim Furyk and Brandt Snedeker.
They were the two Americans they beat at the start of the match, but revenge was sweet as the home pair halved the final two holes for a one-up win.
McDowell, the 2010 match-winner at The Celtic Manor Resort, was then told he was watching the afternoon action, as was Westwood.
Mickelson said: "The European side has had some great team-mates - Seve and Ollie and some others - but to be able to share this experience with Keegan has been really awesome.
"We've had so much fun, the crowd has provided so much energy and it's brought our best golf out."
Bradley added: "I'm just thrilled I get to share this with Phil and play the way we did. And I got to witness on the good side one of those Phil pars on the last hole."
That was a reference to the 12th. Mickelson drove into the trees, forcing his partner to lay up, but then his approach landed on the ridge some 30 feet left of the hole and trickled down to within inches.
Westwood, off on a bad foot when he dumped his tee shot into the water on the second, and Donald had been on in two, but three-putted and so did not win a single hole in a contest they finished three over par against their opponent's six under.
Watson and Simpson, who had five birdies himself in six holes from the eighth, were in sight of victory at four up with five to go and the Americans led in three of the four games.
That was because Colsaerts and Lawrie could not match Kuchar's birdie at the long tenth and so fell behind, while McIlroy and Poulter were two down at the same point.
Woods and Stricker were hit by back-to-back birdies from Donald at eight and nine, but Woods did at least birdie the next to cut the deficit back to three.