The Swiss number two Stanislas Wawrinka is into the semi-finals of the ATP World Finals. Wawrinka beat David Ferrer 6-7 6-4 6-1 this afternoon and then needed Nadal to beat Tomas Berdych in the final group A match. Nadal finally came through in a tough three set match 6-4 1-6 6-3. In group B the defending champion Novak Djokovic is already through to the semi- finals and will be joined by Juan Martin Del Potro or Roger Federer who play each other tomorrow afternoon.