US star Jessica Pegula has launched her season by making the quarter-finals while top seed Elena Rybakina saw off her sternest test of the year to also make the last eight of the Adelaide International.
Bernarda Pera's powerful left hand, which took her to an upset victory over former world No.2 Paula Badosa in the opening round, also shook her American compatriot Pegula in the early stages of their round-of-16 clash on Wednesday.
But second-seeded Pegula found her rhythm in the second set, crunching 11 winners to six unforced errors, before digging deep in the third to prevail 4-6 6-2 6-3.
In the evening session, world No.3 Rybakina, fresh from her triumph in Brisbane, continued her fine form by ousting Spaniard Cristina Bucsa 6-3 7-5.
World No.5 Pegula was left in awe of Pera's power in their contest, admitting: "She was hitting unbelievable shots in the first set. I didn't really think there was much more I could do.
"I stayed relaxed and tried not to get frustrated. I want to keep improving and have a good mindset.
"It's a brand new year and I want to find my confidence for the Australian Open."
Pegula has made the quarter-finals of the past three Australian Opens.
Rybakina, the 2022 Wimbledon champion and finalist at last year's Australian Open, dropped just 15 games in five matches en route to a dominant sixth career title in Brisbane last week but was forced to dig deeper against the crafty Bucsa.
"It was a bit tough to get used to the conditions and we're playing late," Rybakina said.
"She played really well today, especially coming forward - you don't see this much so it was a bit surprising for me."
"Hopefully, I can continue like this and will be at my best in Melbourne."
Rybakina will next tackle Russian Ekaterina Alexandrova, who upset eighth-seeded compatriot Veronika Kudermetova 6-4 6-4, for a spot in the semi-finals at Memorial Drive.
Pegula will face French Open runner-up Anastasia Pavlyuchenko after the Russian shrugged off a slow start and a second-set hip concern to defeat Czech Katerina Siniakova 2-6 6-3 6-2 in a third-round battle of the qualifiers.
Siniakova, coming off a shock opening-round rout of countrywoman Karolina Pliskova, was on song early before progressively losing her way on serve, dishing up 12 double faults.
Veteran Laura Siegemund, part of Germany's United Cup-winning team, continued her dream start to 2024 by advancing past Romanian Ana Bogdan 6-4 7-5.
Ukrainian prodigy Marta Kostyuk edged out American Taylor Townsend 6-3 2-6 6-4.
Awaiting Kostyuk in the quarter-finals will be sixth seed Jelena Ostapenko, who fought off leg pains and the stiff challenge of French shotmaker Caroline Garcia to prevail 6-4 5-7 6-4.
