John Isner’s big serve and solid forehand proved too strong for Jo-Wilfried Tsonga as he beat the Frenchman 6-3 7-6 (7-4) 5-7 6-3 on Sunday to ease 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 US team’s momentum after winning Saturday’s doubles in straight sets, without facing a break point, while the pressure was clearly on the sixth-ranked Tsonga to level the match.

Later, Gilles Simon was scheduled to play the 19-year-old Ryan Harrison in the meaningless final rubber at the Monte Carlo Country club.