Rory McIlroy called for a foul-mouthed fan to be ejected and found a potential long-term Ryder Cup partner in inspired rookie Thomas Pieters - but Europe's bid for an historic victory suffered a setback at hostile Hazeltine.
After being whitewashed in Friday's opening session, Darren Clarke's side hit back to win three of the afternoon fourballs and they maintained that momentum on Saturday to win two and a half points from the morning foursomes.
McIlroy and Pieters, who was living up to his billing from Clarke as a future world number one, then combined for nine birdies and an eagle to beat Dustin Johnson and Brooks Koepka and level the overall match score.
However, Clarke's decision to partner Danny Willett with Lee Westwood and split up the Spanish pairing of Sergio Garcia and Rafa Cabrera Bello backfired badly, a decision compounded as top pairing Henrik Stenson and Justin Rose also lost 2&1 to a brilliant Patrick Reed and Jordan Spieth.
That left the holders trailing 9 1/2 to 6 1/2 heading into Sunday's 12 singles matches and needing a comeback similar to the 'Miracle of Medinah' in 2012 to claim an unprecedented fourth straight win.
All square with two to play, Willett and Westwood contrived to both bogey the short 17th, before Westwood missed from two feet for birdie on the last to escape with half a point.
Garcia and Cabrera Bello had recovered from four down with six to play against Reed and Spieth in the foursomes, but Kaymer managed just two birdies in the fourballs alongside Garcia as they went down 2&1 to Phil Mickelson and Matt Kuchar.
McIlroy and Pieters had raced into a four-hole lead at the turn, but that did not sit well with some sections of the home crowd and while McIlroy walked to the eighth tee a male spectator yelled an obscenity directly at the Northern Irishman, according to a number of on-course reporters who were following the match.
A video clip posted on Twitter showed McIlroy doubling back - with some fans urging him to carry on walking and others calling for the offender to be kicked out - and confronting the man before then asking security to remove him. Reports later suggested that had happened.
"Someone just said a few derogatory things I thought were over the line," McIlroy said after a third straight win alongside 24-year-old wild card Pieters.
"I tried to get him removed. I'm not sure if he was removed or not but these things happen.
"It is golf at the end of the day. You try to keep your utmost for who you are playing and for who you are supporting. That particular guy, who is obviously in a very, very, very small minority, just took it a bit too far.
"It's a tough environment but we expect that. You have to keep your concentration out there and it's been a long day and sometimes emotions run high.
"It fuelled me a lot. The more they shouted, the better we played, so I hope they shout at us all day tomorrow."
European vice-captain Ian Poulter criticised spectators' behaviour on Twitter.
The United States have never lost a home Ryder Cup after winning the opening session - but Europe were in the ascendancy when play resumed on Saturday and McIlroy and Pieters provided the early fireworks with a 4&2 win over Mickelson and Rickie Fowler.
Brandt Snedeker and Koepka then enjoyed their second win together, this time over Stenson and rookie Matt Fitzpatrick, before Rose and rookie Chris Wood held their nerve to beat Jimmy Walker and Zach Johnson on the 18th and Garcia and Cabrera Bello snatched their unlikely half against Spieth and Reed.
McIlroy had lost his previous three Ryder Cup matches against Mickelson and admitted: ''When I saw the draw last night I was like 'yes, I get to have a go at him again'. I maybe wanted it a little bit more for that reason.
''Darren put a lot of faith in us in foursomes as we'd not really practised together. We flipped for it on the first tee to see who would hit on which hole.''
That, of course, was not an issue in fourballs and five birdies and an eagle in nine holes had the European pair four up at the turn on their way to a 3&1 victory.
With Westwood carding a hat-trick of birdies from the sixth and Rose and Stenson briefly ahead in match four, Clarke might have been dreaming of ending the day on level terms.
But that dream became a nightmare as Reed fired five birdies and an eagle to lift a lethargic Spieth to victory, before Westwood and Willett's dreadful finish left the holders with a mountain to climb.
"It's been done before from a worse position," Clarke said, a reference to the 10-6 deficit overturned at Medinah. "There is a precedent and we have to have belief."