Maria Sharapova's hopes of becoming the year-end world number one went up in smoke Tuesday when she crashed in straight sets to Petra Kvitova at the WTA Finals in Singapore.
The Russian superstar needed a win to have any chance of overtaking top-ranked Serena Williams but she blew up in spectacular fashion as Kvitova won 6-3, 6-2 in 75 minutes.
It was the second upset in quick succession at the season finale after Simona Halep stunned Williams 6-0, 6-2 on Wednesday, the 18-time Grand Slam-winner's worst defeat in 16 years.
Kvitova's first win over Sharapova since 2011 also left the Russian's bid for a second year-end title -- a decade after the first -- hanging by a thread after her opening defeat to Caroline Wozniacki.
Earlier, Wozniacki beat Agnieszka Radwanska of Poland 7-5, 6-3 to take top position in the White Group round robin as the resurgent Dane neared a spot in the semi-finals.
Sharapova won the first two games against Kvitova but then went to pieces as the Wimbledon champion won the next five straight and took the first set 6-3.
Another run of five games put Kvitova on the verge of victory before Sharapova finally earned a break of her own, and then saved two match points as she clung on in a 10-minute hold of serve at 5-1 down.
However, her resistance was broken when on the third match point, Kvitova blasted a magical looping forehand which landed on the baseline and beyond the crestfallen Russian.
Wozniacki took more than three hours to beat Sharapova on Tuesday and another long match looked likely when she fought with Radwanska in a tight opening set which featured five breaks of serve.
But the super-fit former world number one, who is training for the New York marathon, raced through the second set to step towards her first semi-final at the year-ender since 2009.
"I knew from the start that this wasn't going to be an easy match," Wozniacki said.
"I came out there a little bit nervous, but you know, I just did my best out there," added the world number eight.