Nov. 25 (Bloomberg) -- Robin Soderling, a last-minute substitute at the ATP World Tour Finals, became the first player to qualify for the semifinals by beating defending champion Novak Djokovic.

The ninth-ranked Swede defeated the third-ranked Serb 7-6 (7-5), 6-1 at the O2 arena in London. Soderling, 25, beat Rafael Nadal in straight sets in his first match in Group B. The second-ranked Spaniard plays Russia’s Nikolay Davydenko later today.

Soderling was added to the end-of-season tournament when a knee injury forced Wimbledon runner-up Andy Roddick to withdraw.

“I won two matches in straight sets against the world No. 2 and No. 3,” Soderling said at a news conference. “I couldn’t have asked for anything more. So far I’m enjoying it a lot.”

He is the first Swede to reach the semifinals since Jonas Bjorkman in 1997.

In May, Soderling handed Nadal his first defeat at the French Open before losing in the final to Roger Federer. He entered the top 10 of the ATP’s world rankings last month for the first time.

“I didn’t enjoy playing today’s match, that’s for sure,” Djokovic said. “He was serving really well. All credit to him.”

Soderling could have had an even easier day. He had three set points on the Serb’s serve in the first set, leading 5-4 before he allowed Djokovic to come back to tie it 5-5. In the tiebreaker, Soderling led 6-4 before hitting a forehand return long, then took the set with an ace, one of 10 for the match. He broke the former Australian Open champion early in the second set and cruised to victory.

Djokovic, who had won back-to-back tournaments coming into the London finals, said he was tired after going to three sets to beat Nikolay Davydenko in his first match.

“He has nothing to lose,” Djokovic said about Soderling. “He won four straight sets, and absolutely deserved to qualify for the semifinals. He’s the best player so far in the tournament.”

To contact the reporter responsible for this story: Danielle Rossingh at the O2 arena through the London sports desk at drossingh@bloomberg.net

Last Updated: November 25, 2009 14:30 EST