Singapore - Denmark's Caroline Wozniacki all but booked her place in the semi-finals of the WTA Finals with an impressive 7-5 6-3 win over Agnieszka Radwanska on Thursday.
Showing no signs of fatigue after her exhausting three-set win over Maria Sharapova two days earlier, Wozniacki rebounded from a slow start to overrun Radwanska with an ominous display.
Wozniacki was down an early service break in the opening set but quickly got back on terms and proved too strong for Radwanska, running the Pole ragged on Singapore's purple hardcourts.
With one group match still to go against Wimbledon champion Petra Kvitova, Wozniacki is almost certain to reach the semi-finals for just the second time in the elite season-ending championship.
Wozniacki went all the way to the final in 2010 when she was ranked number one in the world but failed to qualify in each of the next three years as her game started to unravel.
The 26-year-old has seen fortunes turn around in recent months, however, since splitting with her fiance, Northern Irish golfer Rory McIlroy.
Seemingly rejuvenated, she reached the final of the US Open in New York for the second time to qualify for the lucrative WTA finals.
Sharapova and Kvitova were due to square off later on Thursday with both needing a win to stay in contention for the semi-finals.
World number one Serena Williams was scheduled to meet Eugenie Bouchard in the feature night match, just 24 hours after she suffered her heaviest in 16 years against pint-sized Romanian Simona Halep.