Simon was called up to replace injured Gael Monfils this week. He has never beaten Isner and could not cope with the American’s big serve. Simon also struggled with his own service game on the outdoor clay at Monte Carlo Country Club.
“I took to the court very confident,” Isner said. “I played very well. Simple as that.”
The doubles Saturday in the best-of-five series pits Bob and Mike Bryan against Frenchmen Julien Benneteau and Michael Llodra.
“We’d love to be up 2-0, but 1-1 seems just about right and tomorrow will be a great doubles,” United States captain Jim Courier said. “John did what he is supposed to do, which is to be emphatic and dominant.”
The Bryans, the world’s top-ranked doubles pairing, are unbeaten in Davis Cup since losing to France in 2008, when Llodra was partnered by Arnaud Clement.
“The doubles will be decisive,” France coach Guy Forget said. “We’ll be in a great position if we win. If we lose, it will be difficult.”
In the other quarterfinals, host Czech Republic led Serbia 1-0; Spain was up 2-0 on visiting Austria; and Croatia played at Argentina. The semifinals are in September.
“I didn’t really serve that great today, I could have made more first serves,” Isner said. “But my forehand was on and I was going for it. I wasn’t holding back and that was the game plan.”
The 11th-ranked Isner took a grip on the match when a double-break point put him 4-0 up in the second set. With the crowd watching on in resignation, Simon got only a ripple of applause after finally holding to make it 4-1.
The third set was more competitive, but Simon failed to take his chances when they came — including one at set point.