WASHINGTON, Aug 16: Defending champion Andy Roddick was upended in the quarter-finals of the Washington Classic on Friday, beaten 0-6, 6-2, 6-4 by Serbian world number 93 Viktor Troicki.

The top seed blitzed through the opening set but lost his way as Troicki battled into his first semi-final this year, where he will play Russian Igor Kunitsyn, who ended the run of Indian qualifier Somdev Varman with a 6-4, 6-1 victory.

Second seed Argentine Juan Martin Del Potro had no such trouble, felling American John Isner 6-4, 6-4 to extend his winning streak to 17 matches.

He will now play German fourth seed Tommy Haas, a 7-5, 6-1 winner over unseeded Colombian Alejandro Falla.“My serve was terrible,” Roddick told reporters.

“He picked up his game and definitely played well in the third set, but I served I don’t know how many double faults all week. I never normally do double faults. It’s totally unacceptable.”

Roddick raced through the first set against a clearly nervous Troicki without dropping a game.

However, after missing a chance to go 2-0 up in the second, three-time champion Roddick lost his concentration and allowed Troicki, cleverly varying his pace, to level the match.

Roddick then saved a break point in the opening game of the deciding set before the match was interrupted for more than an hour because of rain.

When the players returned, games stayed on serve until the seventh, when Troicki snatched the break as the American shanked a forehand long.

The Serbian then held his nerve to serve out for victory three games later.

Earlier, Del Potro broke the 6ft-9in Isner’s serve once in each set to advance to the last four.

The 19-year-old, who beat Roddick to win the Los Angeles title last weekend after victories in Stuttgart and Kitzbuhel, was too consistent and mobile for last year’s runner-up.

However, Del Potro warned that fatigue was setting in after completing his seventh match in nine days.

“I am very tired and tired in my head,” Del Potro told reporters. “But I want to keep winning matches and tomorrow I have the opportunity to get to another final, so I am very happy.

“His serve is very difficult to return,” Del Potro said of the American. “I tried to move a little bit when he was serving, hoping he would be disturbed a little, and I broke him twice.”

Former world No 2 Haas, who had more surgery on his troublesome shoulder earlier this year, found himself 4-1 down to Alejandro Falla of Colombia before bouncing back for a place in the last four.

“He came out really strong, but once I went a double-break down, I started to feel a lot better and he got a bit tight,” Haas told reporters.

Haas said he would have to play well to stand a chance against Del Potro.

“I think I am going to have to mix it up,” he said. “He is the man to beat really and is very solid, but I think I have the game and I just need to take my opportunities.”

Friday’s results (prefix number denotes seeding):

Quarter-finals: Igor Kunitsyn (Russia) bt Somdev Varman (India) 6-4, 6-1; Viktor Troicki (Serbia) bt 1-Andy Roddick (US) 0-6, 6-2, 6-4; 4-Tommy Haas (Germany) bt Alejandro Falla (Colombia) 7-5 6-1; 2-Juan Martin del Potro (Argentina) bt John Isner (US) 6-4, 6-4.

MAURESMO EASES THROUGH

CINCINNATI (Ohio): Amelie Mauresmo moved a step nearer to winning her first tournament back from an injury layoff when she eased to a 6-2, 6-4 win over American Vania King in the quarter-finals of the Cincinnati Open on Friday.

The former world No 1 coughed up seven double-faults but was still too strong for King as she advanced to a semi-final against fellow Frenchwoman Nathalie Dechy, a 7-6, 7-5 winner over sixth seed Aleksandra Wosniak.

Mauresmo is playing in her first event since picking up a thigh injury at Wimbledon and has slipped to 35th in the rankings.

However, King was unable to take advantage of her opponent’s errant serving and Mauresmo ran out an easy winner in one hour, 18 minutes.

Dechy’s surprise win over Canada’s Wozniak put her into a semi-final for the first time this year.

Second seed Nadia Petrova will play No 3 seed Maria Kirilenko in an all-Russian clash in the second semi-final.Petrova cruised past American wildcard Liliah Osterloh 6-2, 6-3 but Kirilenko had to struggle before overcoming Germany’s Sabine Lisicki 6-2, 1-6, 6-1.

Results:

Quarter-finals: 5-Amelie Mauresmo (France) bt Vania King (US) 6-2, 6-4; 2-Nadia Petrova (Russia) bt Lilia Osterloh (US) 6-2, 6-3; Nathalie Dechy (France) bt 6-Aleksandra Wozniak (Canada) 7-6 (7-4), 7-5; 3-Maria Kirilenko (Russia) bt Sabine Lisicki (Germany) 6-2, 1-6, 6-1.—Reuters