Saturday was a red letter day for Australian tennis as Ashleigh Barty fought back to beat eighth-seeded Kiki Bertens and reach the final of the China Open in Beijing.

And across the China Sea, John Millman was doing likewise, powering  into the Japan Open final by defeating American Reilly Opelka in straight sets.

In what is the biggest challenge of his blossoming career, Millman will now vie for the title with world No.1 Novak Djokovic.

Barty’s victory in Beijing did not come so easily.

The French Open winner took the  first set 6-3, only to drop the second by the same margin, before holding off Bertens 7-6 (9-7) in the deciding third set.

Barty overcame a service break early in the third, clawed her way back from 0-3 in the tiebreak and saved one match point.

Bertens also saved an initial match point in a tiebreak thriller before Barty wrapped up the encounter in two hours 20 minutes.

It is Barty’s 19th win in a three-setter this year and her third in a row after beating Zheng Saisai in the last 16 and seventh seed Petra Kvitova in the quarter-finals, with both matches lasting more than two hours.

“I enjoy those moments. I enjoy when it’s tight, when your back’s against the wall,” Barty said after her fifth career win over Bertens. “That really brings out the fun for me.

“It’s just been really nice to be able to play (these) two matches the last two days – incredible level. Regardless if I was on a plane home today, I probably wouldn’t have stressed any more or less about it.”

In a see-saw match, both players dropped serve three times with little to separate the two until the tiebreak decider.

Bertens first saved a match point with a long rally to level points at 6-6 before Barty fought back to 7-7. She forced the Dutchwoman into an error and won the match on her next match point.

“I think it was a great match, great fight from both sides,” Bertens said.

“It could go either way. It was not me today. I played the right way; I was coming forward; I played aggressive where I could.”

Barty will play Japan’s Naomi Osaka or defending champion Caroline Wozniacki of Denmark.

-with AAP