LONDON (AP) -- Rafael Nadal held off Tomas Berdych 6-4, 1-6, 6-3 to finish the round robin 3-0 and win his group at the ATP World Tour Finals, allowing Stanislas Wawrinka to join him in the last four.
Wawrinka beat David Ferrer 6-7 (3), 6-4, 6-1, but needed Nadal to win to advance to the semifinal.
Nadal lost his grip on the match in the second set, dropping his serve twice. The Spaniard had already qualified from Group A after winning his first two matches, clinching the year-end No. 1 ranking the process.
Nadal only needed to claim a set against Berdych to clinch the group win. But he broke him in the eighth game of the third set after Berdych double-faulted twice.
''I wish him a good holiday and good luck for the Davis Cup,'' Nadal said of Berdych, who will be playing in next week's Davis Cup final between defending champion Czech Republic and Novak Djokovic's Serbia in Belgrade. ''In the second set he played great, it was very difficult to stop him.''
Against Ferrer, Wawrinka hit 35 winners, including 12 aces, to clinch his second win at the season-ending tournament.
"For sure, I'm going to be a big fan of Rafa," said No. 8 Wawrinka, who is enjoying a breakthrough season after years in the shadow of Swiss star Roger Federer. "I did my job all week. I did the best I can, so now I'm just going to watch what is going to happen and I'll be really happy if Rafa wins tonight."
Nadal, who clinched the season-ending No. 1 ranking this week, has already qualified from Group A after winning his first two matches without losing a set.
Defending champion Novak Djokovic has won Group B. The winner of Saturday's match between Juan Martin del Potro and Federer will join him in the semifinals.
Two unforced errors by Ferrer in the first game of the third set gave Wawrinka an early break, and the U.S. Open semifinalist hit three aces in the next game for a 2-0 lead.
Wawrinka broke again for a 4-1 lead and closed out the match with a backhand after Ferrer misplayed an easy volley.
Defending champion Novak Djokovic has won Group B. The winner of Saturday's match between Juan Martin del Potro and Roger Federer will join him in the semifinals.
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