( CNN ) -- Rafael Nadal completed a perfect sweep of his matches in Group A of the ATP World Tour Finals by beating Tomas Berdych Friday -- his victory enabling a grateful Stanislas Wawrinka to accompany him into the semifinals in London . Wawrinka and his supporters breathed a sigh of relief after Nadal wrapped up a 6-4 1-6 6-3 victory over his Czech opponent to go through as group winner . The match had been in the balance when Berdych hit back to level at one set all with a display of power tennis that had the top seed wobbling , but he could not sustain the effort . Nadal , who has never won the end of season showpiece , waited until the eighth game of the decider to make the breakthrough , taking advantage of two double faults by fifth seed Berdych . He then served out for victory , completed with a flashing forehand winner and customary fist pump . Nadal was also fully aware he had done Swiss star Wawrinka , who is making his debut in the finals , a big favor . `` I have a great relationship with him , so I 'm happy for Stan , sorry for Thomas , '' Nadal said . `` Before the match Stan came to the locker room and told me 'come on ' , `` he revealed . Wawrinka , who would have been on the edge of the seat as Berdych made his move , tweeted : Vamooooos ! ! ! Next diner is for me @ RafaelNadal ! ! Good job ! ! He had earlier battled past Nadal 's compatriot David Ferrer in a thrilling afternoon match at the O2 Arena . Wawrinka , who beat Berdych in his opening match before losing to Nadal , raced into a 5-2 lead in the opener before Ferrer battled back to force a tiebreaker , which he took 7-3 . But Wawrinka hit back to level the second set with a single break and then dominated the decider with two further breaks , sealing a 6-7 6-4 6-1 victory . Saturday will see Group B decided with Roger Federer taking on Juan Martin Del Potro to decide who goes through to the last four with defending champion Novak Djokovic . The Serb plays Richard Gasquet , who has already been eliminated .
Stanislas Wawrinka qualifies for semifinals at ATP World Tour semifinals . Beats David Ferrer in three sets in Group A. Rafael Nadal 's win over Tomas Berdych seals Wawrinka 's passage . No.1 Nadal has to battle past Berdych in three sets .