John Isner's big serve and solid forehand proved too strong for Jo-Wilfried Tsonga, defeating the Frenchman 6-3, 7-6 (4) 5-7, 6-3 Sunday to put the United States into the Davis Cup semifinals.
Tsonga had chances, but could only break his serve once as the Americans took an unassailable 3-1 lead, setting up a match against either Spain or Austria for a place in the final.
Isner built on the U.S. team's momentum after a straight-set doubles win on Saturday.
He didn't face a break point, while the pressure was clearly on the sixth-ranked Tsonga to even the score at the Monte Carlo Country club.
Later, Gilles Simon was scheduled to play 19-year-old Ryan Harrison in the meaningless last match.