"That match to me just personifies it," said McDowell. “You're playing against two very gutsy players who clawed their way back.
"But we had stacked our team with this finish in mind. I wanted Rory hitting the tee shots on 16 and 18 and our strategy paid off."
McIlroy added: "Fortunately for us, Brandt didn't hit the best tee shot on the last."
Lee Westwood and Francesco Molinari were only one down with three to play, but Westwood drove right into water and they lost the 16th as well to go down 3 and 2 to Jason Dufner and Zach Johnson.
In the last match out Ian Poulter and Justin Rose were faced with a distinctly off-colour Tiger Woods, and despite the best efforts of Steve Stricker, were able to win 2 and 1.
Three up with four to play, Stricker and Woods took the 15th and looked like taking the long 16th when Woods found the green in two.
But Poulter bravely holed a 15 foot clutch putt and when Rose lagged a 30 footer to the side of the hole at the next it sealed victory and left the contest poised at 2-2.
Poulter took his cup record to nine wins in 12 games, but two of the three defeats had come against Woods and he said: "I never wanted wanted to have another one."
Both Captains sent out unused pairings in the opening afternoon fourballs session, with Paul Lawrie and Peter Hanson taking on Bubba Watson and Webb Simpson.
The second game had all the ingredients of a classic as in-form Bradley and Mickelson were sent back out to face World Number One McIlroy and compatriot McDowell.
Davis Love sent out another pair who sat out the morning’s action in Dustin Johnson and Matt Kuchar in game three, and they faced Rose and new partner Martin Kaymer.
Despite their struggles in the morning Woods and Stricker retained the anchor role for the US, while Nicolas Colsaerts was given his first taste of Ryder Cup action alongside Lee Westwood.
The Americans won seven of the first eight holes as the match resumed.
Lawrie and Hanson were three down after four to Watson and Simpson, McIlroy and McDowell could not stop Mickelson and Bradley going three up after three and Woods got in on the act with an opening 18 foot birdie putt.
Coming off the seventh green Watson and Simpson, who won three of their four games together at last year's Presidents Cup, were already five up.
But McIlroy and McDowell had their first success on the sixth to be back to only two down and the bottom two games were level after four and three holes.