TOKYO — Tomas Berdych defeated Andy Roddick 6-7 (2), 7-5, 7-6 (3) in the semifinals of the Japan Open today, ending the seecond-seeded American's bid for a second straight title in Asia.

The ninth-seeded Berdych will face fifth-seeded Juan Martin Del Potro of Argentina in Sunday's final. Del Potro defeated No. 4 Richard Gasquet 6-3, 4-6, 7-5 in the other semifinal.

Roddick, coming off a win at the China Open last Sunday, broke Berdych to take a 2-0 lead in the final set and looked set for another trip to the finals after building up a 5-2 lead.

However, Berdych staged a dramatic comeback in his second consecutive trip to the tournament semifinals.

After holding serve in the eighth game, Berdych broke Roddick with a crosscourt forehand to close the gap to 5-4 before sending the final set into a tiebreaker, which he won with an ace.

"Being down 5-2 doesn't look good," Berdych said. "But it was only one break. I just tried to stay on my serve and look for a break and finally it came and I could finish the set."

Roddick also had a chance to win in the second set. With the score tied 5-5, Roddick double faulted to give Berdych a 6-5 lead. He slammed his racket on the court and was given a warning.

"It's disappointing," Roddick said. "I don't know how to rate it. You feel like you have a match in your grasp and then let it go."

Roddick, who had 25 aces, said Berdych made the most of his chances.

"He hit some good shots," Roddick said. "I don't think I missed any easy shots. He played a good game and this surface suits his game because he hits the ball hard and flat."

Berdych, 23, is chasing his first singles title this year and fifth of his career.

Earlier, Del Potro extended his extraordinary run of form by beating Gasquet in three sets.

The 20-year-old Del Potro has now won 29 of his past 30 matches, with the only loss being to eventual finalist Andy Murray in the U.S. Open quarterfinals.

During that streak, he has won titles at Stuttgart, Kitzbuhel, Los Angeles and Washington, having not won any singles titles before.

In the women's event, top-seeded Caroline Wozniacki of Denmark coasted to a 6-4, 6-3 win over Jarmila Gajdosova of Slovakia to reach the final. She will take on fifth seeded Kaia Kanepi of Estonia, who defeated Canada's Aleksandra Wozniak 6-4, 6-4 in the other semifinal.

Wozniacki is chasingher third singles title in as many months, having claimed the events in Stockholm and New Haven.

Kanepi is into just her second career final, having been a runner up in a Belgian event in 2006.