* Americans take foursomes session 3-1 to tighten grip
* Mickelson and Bradley win third match together
* Europe's big guns fail to fire (Updates after foursomes session)
MEDINAH, Illinois, Sept 29 (Reuters) - Phil Mickelson and Keegan Bradley set the tone in record equalling style as the United States took a commanding 8-4 lead over holders Europe after dominating Saturday morning's foursomes at the Ryder Cup.
Though Europe had sent out all their big guns in the alternate-shot format in a bid to wrest back momentum in the biennial team competition, the fired-up Americans won the session 3-1 in dazzling sunshine at Medinah Country Club.
Cup veteran Mickelson and rookie Bradley won their third match of the week together, piling up six birdies as they handed out a 7&6 thrashing to out-of-form Englishmen Lee Westwood and Luke Donald.
Their margin of victory matched the wins earned by Hale Irwin and Tom Kite over Ken Brown and Des Smyth at the 1979 Ryder Cup, and by Paul Azinger and Mark O'Meara over Nick Faldo and David Gilford in 1991.
Jim Furyk and Brandt Snedeker never trailed on their way to a 1 up win against Northern Irishmen Rory McIlroy and Graeme McDowell while Zach Johnson and Cup rookie Jason Dufner beat Belgian Nicolas Colsaerts and Spaniard Sergio Garcia 2&1.
Europe's sole consolation came in the top match where Englishmen Justin Rose and Ian Poulter clawed their back from one down after eight holes to defeat Bubba Watson and Webb Simpson 1 up after a tight battle.
U.S. Open champion Simpson had a chance to square the match on the 18th green but he narrowly missed a birdie attempt there from just six feet.
"I feel like we actually didn't have our best stuff today and to win that point was massive," a jubilant Rose told reporters.
Earlier in the day, a plane flew across the skies above Medinah with the sky-writing message "Do it for Seve (Ballesteros)" trailing in its wake but that plea for a much-needed European resurgence never materialised.
Mickelson and Bradley had triumphed twice together on the first day amid a flurry of fist pumps and high-fives and they continued that sizzling form with five birdies on the front nine.
Bradley, winner of last year's PGA Championship, sank a curling 12-footer to birdie the par-four ninth before furiously pumping his right fist as the crowd erupted in deafening cheers.
The U.S. duo went six up at the 10th before sealing victory with a scrambling par at the 12th where Mickelson struck his approach to within a foot of the cup and the Englishmen bogeyed.
"We've had so much fun," smiled Mickelson, who is playing in a record ninth Ryder Cup for the U.S. this week. "The crowd has provided so much energy, and it's brought our best golf out."
Bradley, who has been mentored by Mickelson since he made his debut on the PGA Tour last year, said: "I'm just thrilled I get to share this with Phil and play the way we did.
"I got to witness on the good side of one of those 'Phil pars' on the last hole."
It was Donald's second foursomes defeat this week after he had been unbeaten in the format in six previous Ryder Cup matches.
"We just kept pushing and trying as hard as we could, but they kept coming up with great shots," said the former world number one.
The Europeans desperately need to spark during Saturday afternoon's fourball matches but they face a daunting task with a greater percentage of the American players displaying superior form at Medinah this week.