Dufner and Johnson secured the win 3 and 2, meaning they had an insurmountable three-hole lead with two remaining at Medinah Country Club outside Chicago.
The U.S. leads the matches 2-1. Phil Mickelson and Keegan Bradley beat the European team of Luke Donald and Sergio Garcia 4 and 3, before Europe tied the score when Rory McIlroy and Graeme McDowell beat Americans Jim Furyk and Brandt Snedeker 1- up on the final hole.
Teammates in foursomes hit alternate shots.
The afternoon session will feature fourballs, in which each golfer in the two-man teams plays his own ball, with the lowest individual score winning the hole. The competition continues through Sunday.
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