Davydenko beats Del Potro to reach semis

SHANGHAI (Reuters) - Russian Nikolay Davydenko outslugged Argentine Juan Martin Del Potro 6-3 6-2 in a winner-takes-all battle for a place in the semi-final of the Masters Cup Thursday.

The 27-year-old joined Novak Djokovic and Andy Murray in the last four, reaching the knockout stage for the second time in four appearances at the season finale for the top eight players in the world.

"I feel great," said Davydenko, who lost his opening Gold Group match to Djokovic.

"I thought I had a chance to beat Djokovic but I didn't and today was my last chance of getting to the semi-final."

Defending champion Roger Federer must beat Briton Murray on Friday to claim the final place in the last four, which will otherwise go to Frenchman Gilles Simon.

Del Potro, who now heads home for next week's Davis Cup final against Spain, held his own through some long early rallies but once he lost the first set, the long season and a toe injury looked to have caught up with him and he folded.

"I was playing against the number five in the world so the match was always going to be tough," said the 20-year-old world number eight. "But I'm happy because I'm going to Argentina and I have another good thing to play for next week."

Davydenko sent down a couple of aces to win his opening service but otherwise the early games were drawn out affairs with both players happy to slug it out from the baseline.

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The Russian was hitting more winners -- Del Potro managed just seven in the entire match -- and he broke for 3-1 when the Argentine netted after another mammoth rally.

Del Potro, who beat the Russian in the singles to help his country to the Davis Cup final, finally managed to convert a break point to even the set up.

The next game was the best of the match, with Del Potro saving one break point with a beautiful forehand only for Davydenko to run him around the court and volley home for another break three points later.

"I could see Del Potro was nervous after losing the first set," said Davydenko, who won the contest in just under an hour and a half. "In the second, he was not concentrating as well and made more mistakes."

Jo-Wilfried Tsonga earlier restored some pride by coming back from a set down to beat world number three Djokovic 1-6 7-5 6-1 in a dead rubber match in the same Gold Group.

"I take every match seriously and wanted to win this one," said the Serbian, who beat Tsonga to win the Australian Open in January. "The important thing is that I'm through. I think I have enough quality to go further."

Despite going out, the 23-year-old Tsonga was delighted with a season where he reached a grand slam final, won his first title and broke into the world top 10 despite having knee surgery in May and only playing 15 tournaments.

"It's just very good to have years like this," said the world number seven. "With all my problems I played very well."

(Editing by Alan Baldwin)