It took seven match points, but Danielle Collins is through to her second Hologic WTA Tour singles quarterfinal since last March.
The No.10 seed defeated Swiss qualifier Jil Teichmann 6-3, 7-6(2) on Wednesday in Adelaide to seal a berth in the final eight.
Stat of the day: Collins' last quarterfinal result came in October at the San Diego Open. In a stop-and-start 2022 season due to injury, the American only reached three quarterfinals in total despite finishing as runner-up at the Australian Open.
Her other last-eight berth came at the Miami Open, where she was beaten by eventual runner-up Naomi Osaka.
Match management: Collins never lost serve in the first set against Teichmann, though she saved two break points in the eighth game. But she came from 3-1 down in the second set, and won four straight games to put herself on the precipice of victory.
She failed to serve out victory, which set the stage for the contest's most dramatic game. From 0-40 down. Teichmann saved five match points on her serve to knot the second set at 5-5, after six deuces.
Undeterred, Collins later won six of the first seven points of the tiebreak to eventually wrap up victory.
Seeds Bencic, Haddad Maia seal QF spots
Collins' fellow seeds Belinda Bencic and Beatriz Haddad Maia also won in straight sets to reach the last eight. No.8 seed Bencic was a 6-3, 6-3 winner over qualifier Anna Kalinskaya, while No.11 seed Haddad Maia beat lucky loser Amanda Anisimova, 6-4, 7-5.
While Bencic improved her head-to-head record against Kalinskaya to 3-0 with her victory, Haddad Maia broke a winless spell against Anisimova to reach the next round. She'd previously been 0-2 agains the American all-time.
Kvitova through as Zheng Qinwen succumbs to injury
Petra Kvitova kept her perfect 2023 record in tact thanks to an abridged victory over Zheng Qinwen.
After coming from 5-3 down in a 71-minute opening set, and saving three set points in the ensuing tiebreak to win it 8-6, Kvitova moved through when Zheng retired due to a left thigh injury.
Kvitova will next face the winner of the match between No.5 seed Daria Kasatkina and her fellow Czech, Barbora Krejcikova.