Australian Open champions Zhang Shuai/Samantha Stosur earned a comeback victory against Xu Yifan/Gabriela Dabrowski 4-6, 6-4, [10-5] at the WTA Finals Shenzhen on Tuesday.

Zhang/Stosur got an early break to storm to a 3-0 lead out of the gate off consistent first service shooting. But they would begin to slip following this early show of strength, double-faulting twice and surrendering this early lead.

Xu/Dabrowski were undeterred and responded with two breaks of their own to go up 4-3, never facing breaks point again and firing off an ace on the way to serving out the first set in just over half an hour.

The second set was a much more closely-fought affair. Each side held to love on their opening services, but Zhang/Stosur were made to sweat on each of their remaining services on the way to a 4-3 lead, saving a total of nine break points.

This resilience on the part of Zhang/Stosur would prove decisive, as the pair converted a break point to love to break the stalemate and seal the second set to force a deciding tiebreak.

Zhang/Stosur quickly stormed to a 5-2 lead in the tiebreak and never looked back from there, stitching up the win in just under 90 minutes. The pair now have one win and one loss in the purple group round-robin standings.

Later, 2019 Wimbledon champions Hsieh Su-wei/Barbora Strycova outlasted Barbora Krejcikova/Katerina Siniakova, 6-2, 1-6, [10-5].

After two matches for each team in the Purple Group, No.2 seed Hsieh Su-wei/Strycova are currently atop the group and booked a berth in the semifinals. Zhang/Stosur and Krejcikova/Siniakova will face each other on Thursday for the second semifinal spot coming out of their group.

In women's singles, late entry Kiki Bertens, who replaced Naomi Osaka, stunned world number one Ashleigh Barty with a comeback three-set victory.

Osaka pulled out of the tournament with shoulder injury hours before her second match at the year-end championships against Ashleigh Barty.

"I'm disappointed to have to withdraw from the Finals," Osaka said in a statement released by the WTA. "It has been a great event in Shenzhen, and it's the biggest WTA event of the year. This is not how I wanted to end this tournament or my season. I look forward to getting healthy and hope to be back here in Shenzhen next year."

All four players in the Red Group can still qualify for the semi-finals, after Belinda Bencic's three-set victory over Petra Kvitova in the later match.

(With input from agencies)