French Open champion Stan Wawrinka produced a resilient performance to trounce David Ferrer in his second round-robin contest at the ATP World Tour Finals.
Wawrinka, the world number four, recovered from 5-2 down in the opening set to claim a 7-5, 6-2 win over Spain's Ferrer, the Guardian reported.
Wawrinka will next face world number two Andy Murray in a must win contest to qualify for the last four in second place.
Meanwhile, 14-time Grand Slam champion Rafael Nadal topped the Group Ilie Nastase with a emphatic 6-4, 6-1 victory over Murray earlier in the day.