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Juan Martin Del Potro upset top-seeded David Ferrer in straight sets on Friday to advance to the semifinals of the Japan Open.
Argentine Del Potro, seeded fifth, beat the Spaniard 6-1, 7-5, denying the defending champion a chance to repeat at the US$869,000 (605,000) ATP event.
"It was a very tough match against one of the best players in the world," said Del Potro. "He won here last year and has been playing well."
Del Potro will play Richard Gasquet in the semifinals. The fourth-seeded Frenchman defeated Germany's Rainer Schuettler 6-3, 6-2.
American Andy Roddick, the tournament's No. 2 seed, coasted to a 6-3, 6-4 win over Serbian Viktor Troicki to advance to a semifinal showdown with either Tomas Berdych or third-seeded Fernando Gonzalez.
After cruising through the first set, Del Potro broke in the eighth game of the second set to take a 5-3 lead. Ferrer got back on serve, but Del Potro broke in the final game, hitting a crosscourt forehand winner on match point.
"I tried a lot things," said Ferrer. "But Juan Martin is very confident. He's been winning a lot of matches lately and played very well today."
Ferrer had won his two previous meetings with the 20-year-old Del Potro, who has won 28 of his past 29 matches.
Roddick, coming off winning the China Open on Sunday, was in control from the outset against Troicki, who advanced to the quarterfinals on Thursday when his opponent, Jo-Wilfried Tsonga, retired from his third-round match with an abdominal strain.
"That's the best I've played so far," said Roddick. "I didn't serve as well as I have the last couple of days but I played better from the baseline. Hopefully, I can put the two together on the weekend."
In the $175,000 (121,000) WTA event, top-seeded Caroline Wozniacki of Denmark coasted to a 6-4, 6-1 win over seventh-seeded Tamarine Tanasugarn of Thailand to reach the semifinals.
Wozniacki will face Slovakia's Jarmila Gajdosova in the semis. Gajdosova - in the draw as a lucky loser - beat Klara Zakopalova of the Czech Republic 7-5, 7-5.
The other semifinal will be between No. 5 Kaia Kanepi and No. 8 Aleksandra Wozniak. Estonian Kanepi edged Russia's Anastasia Pavlyuchenkova 7-6 (4), 7-6 (1), while Wozniak downed Australian Samantha Stosur 7-5, 6-3.