John Isner defeated Gilles Simon 6-3, 6-2, 7-5 Friday, pulling the United States even with France after opening singles in the Davis Cup quarterfinals.

The Americans needed a strong performance from Isner after Jo-Wilfried Tsonga beat teenager Ryan Harrison 7-5, 6-2, 2-6, 6-2 to give France a 1-0 lead.

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."

Tsonga will face a tough match against Isner on Sunday.

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.

Isner hit nine aces and 53 winners and broke Simon's serve four times. Simon, who dropped to 0-3 against Isner, had 15 winners but failed to convert any of his five break-point chances.

"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.

With Isner trailing 3-2 and 15-40 down in the sixth game, Simon's two-handed backhand flew into the net. Isner was 30-40 on his next service game but saved break point with a smash for 4-4.

Simon kept chipping away and, when Isner missed an easy volley at the net, Simon got his chance to pull back a set with Isner on his second serve. But the American kept his cool, and his forehand winner down the line got him out of danger.

The momentum had turned back in Isner's favor, and his volley on the run gave him break point in the 11th game. After some great defending at the net, he led 6-5 and easily closed out the match.

Neither team is at full strength. Simon was a late call-up for the injured Gael Monfils, while Harrison replaced ninth-ranked Mardy Fish when he pulled out with fatigue this week.

Earlier, the sixth-ranked Tsonga found it tough at times against the 19-year old American, who was playing in his first meaningful Davis Cup match. Harrison's aggressive shot-making forced Tsonga to hurry shots as he tried to shorten the rallies.

"I hope I play better in my next game (against Isner on Sunday)," Tsonga said. "I had to battle and it worked out quite well for me. Despite losing that third set, I still tried to play my own game."

Tsonga broke Harrison in the 12th game to take a laborious opening set in 54 minutes, then began to find his range as Harrison's temper frayed.

"His major weakness is that he is very, very nervy," Tsonga said. "I knew that if I held on longer than him, it would be to my advantage."

Captain Jim Courier spoke with Harrison after the American smashed his racket into the ground following his double fault that gave Tsonga a 3-1 lead in the second set.

"I never double-fault that much, which is funny," Harrison said. "The sun was against me on that side, and so was the wind."

Harrison, ranked 66th and with only one Davis Cup match to his name — a meaningless dead rubber in the 5-0 thrashing of Switzerland in February — was far from intimidated and applied the early pressure.

But when Tsonga broke in the fourth game of the second set for 3-1, Harrison took it out on his racket, whacking it so violently into the ground that the frame bent into a right angle.

It didn't go unnoticed.

"You look at him and think 'OK, he's not feeling great,'" Tsonga said.

It prompted Courier, the former two-time French Open champion, to have a gentle word with Harrison.

Courier then offered a sympathetic ear to the player at the end of the second set, nodding while Harrison spoke as they plotted a way to get back into the match.

"I agreed with him that my balls were landing a bit short, and that (Tsonga) was playing the match on his own terms," Harrison said.

Their chat seemed to work, with Harrison beating Tsonga in the third set, breaking his serve three times.

"I think he's an unpolished diamond," Courier said. "You don't want to snuff out someone's fire. Ryan is a high energy guy, my job is to help him nurture that energy."

But Tsonga drew on his experience and regained control of the match in the fourth set, taking Harrison's serve with a smash and holding for a 3-0 lead.