Sofia, Bulgaria, 3 November 2013 | AFP

Australian fourth seed Sam Stosur has beaten Anastasia Pavlyuchenkova in three sets on Saturday to reach the WTA Tournament of Champions final in Sofia, Bulgaria.

Stosur downed the sixth-seeded Russian 6-1 1-6 6-3 to set up a final showdown with Romanian top seed Simona Halep, who battled back from a double break down in the deciding set to beat Ana Ivanovic 2-6 6-1 6-3.

It will be a rematch of the pair’s recent final at the Kremlin Cup in Moscow, in which Halep ousted Stosur in straight sets.

The Australian needed one hour and 45 minutes to see off Pavlyuchenkova.

She relied on her powerful kick serves to take an early 3-0 lead in the first set against the Russian, who struggled with a very low first-serve percentage.

The 29-year-old Stosur – the oldest player in the tournament – broke Pavlyuchenkova again in the sixth game to win the set.

The two traded breaks at the start of the second set but Stosur lost rhythm and concentration and made a number of unforced errors.

The Russian took advantage, breaking again in the fourth and sixth games and holding serve to take the set.

Stosur recovered in the decider and managed to break a tough Pavlyuchenkova in the fourth game.

The Russian saved a match point in the eighth game before the Australian finally took the set and the match with an ace.

“I didn’t serve well today, but I still won the match,” said Stosur.

“I started great but, in the second set, everything turned upside down. In the third, I gave it all to reach the final.”

“Simona returns incredibly and I’m sure it will be very difficult match (in the final).”

On Sunday, Halep will be chasing her sixth title of 2013.

Ivanovic led 3-0 in the final set but Halep won 25 of the last 32 points to seal victory.

“I played really well when she had break points to make it 4-1, and I’m really happy with the way I came back in the end,” Halep said.

“I’m a little bit injured in my leg but I’m very happy I was able to win. Now I’m going to rest and recover and I hope to just come back and enjoy the final.”

Halep is projected to rise from No.14 to No.11 on the new world rankings.