Ana Ivanovic overcame illness and nerves as she outlasted French Open champion Maria Sharapova 6-2 5-7 7-5 to set up up a final against world No.1 Serena Williams in the WTA Tour’s Cincinnati event.

In the last major tune up for the US Open starting in one week, Ivanovic led by a set and 5-2 but ended up having to save a couple match points before beating Sharapova in their semi-final on Saturday.

Top seed Williams moved within one win of a second pre-Open hardcourt title as she beat Caroline Wozniacki 2-6 6-2 6-4 in her semi-final.

Former world No.1 Ivanovic and Williams will meet the fourth time this season, and it’s not all been one-way traffic as Serb won their clash in a major upset at the Australian Open.

“It will be a very tough one, but first comes recovery,” said Ivanovic. “It is fun to play her and test yourself against the best. It will be a quick turnaround.”

Williams, who claimed her 61st career WTA title at Stanford two weeks ago, is playing a third tournament in a row for the first time since late 2007.

She improved her 2014 match record to 37-6 with the win over Wozniacki.

Ivanovic had to be seen by the doctor in the third set of her match against Sharapova.

The Serb suddenly stopped at 15-all in the second game. She went to the sidelines and lay down for a few moments to receive treatment and then the match continued.

“It was hot and humid and I felt sick in the second set,” said Ivanovic. “But the tablets I got from the doctor worked and I feel better now.”

She admitted she’d struggled with her nerves as well.

“Up a set and 5-2, I got tight,” said Ivanovic. “I was not moving my feet. She’s a great champion and she used her opportunities.

“It was very important for me to get my composure back in the third set.

“My emotions were all over the place. There were a lot of breaks in the final set. Maria is a fighter and never gives up. But I stayed calm.”