INDIANAPOLIS, Indiana (AFP) - Americans James Blake and Sam Querrey lost early momentum, crashing to defeats and leaving Frenchman Gilles Simon and Russian Dmitry Tursunov to contest the final of the Indianapolis Tennis Championships.

Second-seeded Simon stayed steady as fourth seed Querrey suffered a physical meltdown in the final set to lose 6-3, 4-6, 6-4.

The notably fragile Blake opened the door to defending champion Tursunov, returning after a second-set rain break with nothing left on his serve and paying the price 4-6, 6-3, 6-4.

"I don't know what happened," said the distressed top seed, who had been counting on the hardcourt summer to rescue his game after Roland Garros and Wimbledon second-round defeats.

"I didn't have a first serve when I needed it, it's one of those things that can happen unfortunately," said Blake, who clawed back a break in the final set but lost the match as the Russian struck again a game later.

Third seed Tursunov admitted that he remains an unlikely finalist as he defends a title for the first time.

"I'm confident that I can play well," he said of his first meeting with the 25th-ranked Simon.

"If I play well I have my chances - as long as he doesn't blow me off the court. I'll hope to concentrate like I did today and get a good match rhythm."

Tursunov last played a final in Sydney at the start of the year, an event he won for his fourth career trophy. He improved to 23-14 this season.

Simon said he got a lift as Querrey began to fade badly.

"I kept fighting, especially when I could seem him leaning on his racket after points in the third set," said Simon, playing in his first American semi-final. "I could tell he was tired and that kept me fighting."

Simon, who won a third career ATP title in Casablanca in May, improved his season record to 25-16 as he became the first French player since Olivier Delaitre in 1994 to challenge for the Indy title.

The match was a fitness disaster for Querrey, who looked like making an early exit while trailing a set and 4-2.

The Californian whose huge serve produced a mere three aces, somehow rallied in the second set, recovering from a break in the sixth game with a break-back in the seventh for 3-4 as Simon donated a pair of double faults.

He squared the contest at a set each, but then began to fade badly in the third.

Querrey saved three break points to hold for 4-4 in the third, then forced Simon to save five a game later.

But the fitter Frenchman broke in the final game to lift the win.