Daria Gavrilova has continued her strong form in Moscow, while Carla Suarez Navarro can no longer qualify for the WTA Finals.
The Australian secured a quarterfinal berth in the Kremlin Cup after Suarez Navarro retired from their second-round clash.
World No.37 Gavrilova was leading 6-4 3-0 when the Spaniard succumbed to a wrist injury.
Gavrilova is understood to require a quarterfinal win against seventh-seeded Anastasia Pavlyuchenkova to boost her ranking into the top 32, which could deliver her a seeding at the Australian Open in January.
She rallied against world No.12 Suarez Navarro after going down a break early in the first set.
Gavrilova produced several superb winners to hit back from 4-3 down with her opponent on serve to win the next six games of the match.
“I thought I played pretty well. It was a tough battle,” Gavrilova said.
“(There were) a few pretty tough games, I think we played the first four games for like 40 minutes, and then I found momentum.
“I lost my serve at the very beginning, but I felt like I was still in it and I had a lot of chances and then finally it all worked out.”
The result has killed off Suarez Navarro’s hopes of qualifying for the WTA Finals.
Top-seeded Svetlana Kuznetsova remains on course to claim the last WTA Finals place after she beat France’s Alize Cornet 6-4 7-5 in their second-round match.
The Russian was in strong form, landing 76 per cent of her first serves, and next plays Hungarian Timea Babos, seeded ninth.
Kuznetsova will qualify for the WTA Finals only if she wins the Kremlin Cup.
Otherwise, the final place goes to Britain’s Johanna Konta.
In other results, fourth-seeded Elina Svitolina of Ukraine eased past Yulia Putintseva of Kazakhstan 6-2 6-2 and into the quarterfinals.
Svitolina next plays 18-year-old Croatian Ana Konjuh, who had a second-round walkover when Russian qualifier Anna Blinkova was unable to play.
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