US Open winner Samantha Stosur destroyed China's Li Na 6-1 6-0 on Friday to reach the semi-finals of the season-ending WTA Championships for the second consecutive year.
Their last White Group round-robin clash had effectively become a decider to see which of the year's first-time grand slam champions would progress along with Victoria Azarenka but it proved embarrassingly one-sided and was over in 66 minutes.
Australian Stosur will face Petra Kvitova in the last four on Saturday after the Czech recovered from 5-1 down in the first set against Poland's Agnieszka Radwanska to triumph 7-6 6-3 and claim top spot in the Red Group with a 100 percent record.
Radwanska only needed to win one set to reach the semi-finals but her capitulation against the world number three meant Russia's Vera Zvonareva advanced despite winning just one of her three matches.
Zvonareva, who squeezed through via a better games percentage than Radwanska and world number one Caroline Wozniacki after they all recorded one win, will play the in-form Azarenka on Saturday.
World number seven Stosur has, by her own admission, struggled to re-focus since beating Serena Williams in the U.S. Open final at Flushing Meadows last month but she looked back in the groove against Li.
Her topspin serve proved deadly effective and she also displayed some meaty groundstrokes to overpower her listless 29-year-old rival in front of another large crowd at the cavernous Sinan Erdem Arena.
"I'm really pleased with the way I played tonight," said Stosur who lost to Kim Clijsters in the 2010 semis when the event was in its last year in Doha.
"It was a very solid match for me," she told reporters. "I felt really good out there again and hit lots of winners and moved well.
"It was a really good turnaround from the match two nights ago (against Azarenka)."
Having ended a nine-match run against Maria Sharapova without a win earlier in the week, Stosur will be required to do the same against left-hander Kvitova although they have only met twice before.
"I haven't been able to get over the winning line yet against her," Stosur said. "I think she's one of those exciting players to watch because she can pretty much do anything."
Li's crushing defeat was her sixth in six against Stosur as the French Open champion's memorable season ended on a flat note. "My legs just felt really heavy," said the Chinese who did not even bother calling her husband and coach Jiang Shan on to court -- a feature of the WTA Tour these days.
"Today was just not my day."
Azarenka, who dropped just eight games in crushing wins against Stosur and Li, completes the group phase later against alternate Marion Bartoli who will get one match in the big-money event after Sharapova's withdrawal through injury.
The Belarussian still has an outside chance of ending the year at number two in the world rankings although that honour will go to Kvitova should she reach the final.
Wimbledon champion Kvitova produced a series of unforced errors against the tenacious Radwanska, going 5-1 down before stirring into life and rallying to 5-5.
The Pole then edged to within a game of the semi-finals but once the tiebreak began the momentum was with the Czech. Radwanska faded away in the second set but was not too downhearted.
"To be honest even at 5-1 I didn't feel close to winning the set," the Pole explained. "She then started to play unbelievable."