Istanbul - Wimbledon champion Petra Kvitova moved closer to the second biggest title of her career by beating US Open champion Samantha Stosur here Saturday to reach the final of the WTA Championships.
But the incisive left-hander from the Czech Republic had to recover from a set down and from within one point of a break down in the second set against the determined Australian before winning 5-7, 6-3, 6-3.
Kvitova will finish the season as world number two if she goes on to win the title on Sunday, and at her best she looked well capable of it.
But she will be up against another in-form player, Victoria Azarenka, the tall and increasingly more dependable Belarussian who won 6-2, 6-3 against Vera Zvonareva, the former Wimbledon and US Open finalist from Russia.
Azarenka too can become world number two for the first time if she wins the WTA Championship title, but Kvitova will be slight favourite, not least because she won both their meetings this year.
Kvitova's serve was heavy and hard to read, her ground strokes flat and fierce, and her willingness to come to the net was always a threat.
But Kvitova also had a worrying spell after establishing a 4-2 first set lead, during which unforced errors began to spray from her racket.
Stosur's morale levels rose visibly, she broke twice in three attempts to steal the first set, and came close to breaking again.
It wasn't long however before Kvitova improved. The essence of that was playing to her strengths and playing as far up the court as possible.
Fortunately Kvitova came up with a fine first serve when she was 30-40 down in the second game of the second set, when Stosur might have broken and taken control of the match.
It hurtled for an ace, and after Kvitova clung on to that service game, the match took a big change of direction, with the Wimbledon champion breaking serve and twice threatening to make it a double break.
Although Stosur served her way spiritedly out of trouble to avoid going 1-4 down, she was unable to prevent Kvitova breaking through again in the ninth game and levelling at a set all.
Kvitova did that with the help of a good net approach and two rousing forehand drive winners, and they signified that her momentum was increasing.
Sure enough she broke again at the start of the final set when she punished a second serve with a heavy forehand cross court return, and then broke again to love, putting her 4-0 up.
It broke most of Stosur's resistance, and although the US Open champion did enough to pull back one of the breaks, Kvitova comfortably closed out the match at the second attempt, finishing with a lovely drop-lob combination.
Azarenka's win was more straightforward, and might have been more comfortable still, but for a couple of service game blips in the second set.
She struck the heavier drives in a match characterised by baseline exchanges. When Zvonareva found good angles and began to manoeuvre the ball around Azarenka had the physical capacity to run the ball down and contain her.
She lost her early break, but broke serve again in the sixth and the eighth games to take the first set, and had just one moment of danger in the second.
That was when Zvonareva reached 30-40 on Azarenka's serve in the fifth game, was presented with a moderate second serve - and failed to return it.
After that Azarenka was always the likely winner, even when she failed to consolidate her break for 4-2, and finished looking composed and solid.
It was hard to believe that this was the player so disheartened by early season defeats, she considered quitting the game at the age of 22. She now contemplates the biggest title of her career.