WTA Finals: Serena bounces back in Bouchard battering

A day after suffering her heaviest defeat since she was a teenager, Serena Williams was back to her brilliant best as she swatted aside Eugenie Bouchard 6-1, 6-1 in her final round robin match at the WTA Finals on Thursday.

The World No 1 was humiliated 6-0, 6-2 by Romania's Simona Halep on Singapore's purple hard court on Wednesday but put herself on the brink of a semi-finals berth with the crushing victory over her hapless Canadian opponent.

Williams, who beat Ana Ivanovic in her opening match on Monday, has two wins and a loss and needs Halep just to win one set against the Serb to advance to the last four.

Ivanovic faces Halep in the final group game on Friday. Halep is already assured of her place in the semis while Bouchard has been eliminated from the tournament after three straight defeats.

Williams appeared lethargic and lacking motivation in her defeat against the feisty counter-puncher Halep but made sure there would be no repeat of her "embarrassing" loss against the youngest player in the elite eight-woman field.

The 33-year-old forced three break points immediately and while Bouchard battled back to win a game that ensured Halep advanced to the semi-finals, Williams exuded focus and aggression as she set about dismantling her opponent.

"Yesterday was tough for me but I had to put that behind me and my coach really helped me out to recover from that," Williams said in a courtside interview.

"He told me I needed to focus on today and that I was still in the tournament. I actually felt like I was out of the tournament so it was good advice."

Williams gave the 20-year-old a tennis lesson she would not forget over the course of the 59-minute thumping, breaking the Canadian's serve at will to race through the next 11 games to move 6-1, 5-0 ahead in what seemed like the blink of an eye.

Bouchard, who at one stage could only look on in awe as a 205 kph ace zoomed past her, finally stopped the rot and held serve after being broken five straight times to stave off the inevitable but Williams wrapped up the one-sided contest with a huge serve in the next game.

"I decided I was up 4-0 so I may as well go for a big serve and see what happens, I just tried to hit it as hard as I could," Williams said of her monster serve.

Wozniacki nears semis after beating Radwanska

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 U.S. Open in New York for the second time to qualify for the lucrative WTA finals.

Sharapova loses to Kvitova, virtually out of the competition

Serena Williams was on the verge of clinching the year-end World No 1 ranking for the fourth time on Thursday after Maria Sharapova, the only woman with any chance of overtaking her, lost for the second time at the WTA Finals.

Sharapova was beaten 6-3, 6-2 by Wimbledon champion Petra Kvitova at Singapore's Indoor Stadium, leaving her with only the slimmest mathematical chance of leapfrogging Williams for the top spot.

At the every least, the Russian needs to reach the final and rely on Williams bowing out before the final to take the stop spot, but the odds are now heavily stacked against her.

Even if Sharapova wins her final group match against Agnieszka Radwanska, she needs other results to go her way just to make the semi-finals.

Williams previously finished the year ranked number one in the world in 2002, 2009 and 2013.