Rafael Nadal fell out of contention for a spot in the semifinals at the ATP World Tour Finals with a second straight defeat, losing 6-1, 7-6 (4) to Nikolay Davydenko.

Nadal looked sluggish throughout and was thoroughly outplayed by the Russian, who secured his first win of the round-robin phase and can still reach the semis. Nadal, however, will not reach the semis for the first time.

Davydenko broke twice in the first set and was up a break twice in the second at a near sold-out O2 Arena. Nadal then finally came to life, breaking back both times to carry some momentum going into the tiebreaker. However, Davydenko kept his cool and clinched it with a forehand winner on his first match point.

Earlier, Robin Soderling became the first player to reach the semis of the season-ending tournament by beating Novak Djokovic 7-6 (5), 6-1.

Davydenko dominated the first set, dictating play seemingly at will and chasing Nadal from corner to corner with his accurate groundstrokes as the Spaniard grew increasingly frustrated. Nadal slumped his shoulders in despair after double-faulting to go down 0-30 when serving at 4-1, and after losing that game he seemingly gave up on the set. He didn’t bother chasing down Davydenko’s winners in the next game and hardly challenged his serve on set point, letting it whiz by for an ace.

When he went down 30-40 on serve in the first game of the second set, it was enough for someone in the crowd to yell “Wake up!”

The Spaniard did, but it wasn’t enough. He held serve and put up a tougher fight for the rest of the set, but Davydenko was simply too good, finishing with 27 winners to Nadal’s 12 - only three of, which came in the first set.

Soderling outlasted Djokovic in a tense first set despite wasting three straight set points with the third-ranked Serb serving at 4-5. Djokovic then put up little resistance in the second and was broken three straight times, netting a forehand on Soderling’s second match point.

“I won two matches in straight sets against the world No. 2 and No. 3. I couldn’t have asked for anything more,” Soderling said. “So far, I’m enjoying it a lot. But there are still at least two more matches to go. I hope to do really well in those two as well.”

The loss ended Djokovic’s 11-match winning streak, and was his first defeat against Soderling in six encounters. “I think he’s the best player so far in the tournament,” Djokovic said. “I didn’t enjoy playing today’s match, that’s for sure. He was serving really well. All credit to him.”

Soderling led 0-40 at 5-4 but missed a number of shots to keep Djokovic in the set. In the tiebreaker, Soderling took a 6-4 lead with a forehand volley and then converted his fifth set point with a service winner.

He won the last six games of the second as Djokovic grew increasingly frustrated and error-prone.

“That first set was hugely important,” Soderling said. “Then when I got my first break in the second, he didn’t really have the strength to come back.”

More In: Tennis | Sport