Wawrinka qualifies for semifinals at ATP World Tour semifinals . Beats Juan Martin Del Potro in three sets in ATP World Tour win over Tomas Berdych seals Wawrinka 's passage . No.1 ATP World Tour has to battle past London in three sets .
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 .