US Open winner Coco Gauff and defending champion Aryna Sabalenka avoided Day 4 upsets at the Australian Open to advance to the third round along with 16-year-old Mirra Andreeva.
Three-time major finalist Ons Jabeur lost 6-0, 6-2 in 54 minutes to Andreeva in Wednesday's opening match on Rod Laver Arena, and then 2018 champion Caroline Wozniacki also lost to a young Russian on the No. 3 show court.
Two other 16-year-olds lost their center-court matches to highly ranked players: No. 10 Beatriz Haddad Maia accounted for Alina Korneeva 6-1, 6-2, and Sabalenka overpowered Brenda Fruhvirtova 6-3, 6-2 to open the night session.
Gauff extended her winning streak to nine matches at Grand Slams with a 7-6 (2), 6-2 win over fellow American Caroline Dolehide.
Dolehide served for the opening set at 6-5 before Gauff took control in the tiebreaker.
"It was really hard," Gauff said. "If you give her something short, she's going to punish you for it, so if I could go back and do something, I'd change that."
Gauff will next play another American, Alycia Parks, who reached the third round of a Grand Slam singles tournament for the first time with a 7-5, 6-4 win over 32nd-ranked Leylah Fernandez.
Jabeur, the runner-up at Wimbledon in each of the past two years, made 24 unforced errors against Andreeva.
"I was really nervous before the match because I'm really inspired by Ons and the way she plays," said Andreeva, who lost in the final of the junior event here last year. "Before I started on the WTA Tour, I always watched her matches and was always so inspired. Now I had the chance to play against her."
Her opening 7-5, 6-2 win over Bernarda Pera was her first in the main draw in Australia, making her the youngest player since Gauff to win matches at all four majors. Her win over Jabeur was her first over a player ranked in the top 10, another career milestone.
It is the second successive year that Jabeur has lost in the second round in Melbourne.
Wozniacki led by a set and a break before losing 1-6, 6-4, 6-1 to 20-year-old Maria Timofeeva, who is making her main draw Grand Slam singles debut.
Wozniacki, who had two children before returning to the WTA Tour in 2023 after 3½ years away, started out on top before Timofeeva turned the match around with some devastating hitting, including 40 winners.
"I'm really a bit speechless now," Timofeeva said. "It was an honor to play here against Caroline. I was going into the match without any expectations. I enjoyed every second of it."
Timofeeva said she was shocked after seeing her Instagram follower count double in the wake of her win.
"I just checked the Instagram. I was like, 'What the hell happened'? I was doing mine for like three years," Timofeeva told reporters. "I had 5,000 followers. Now I opened. I gained 8,000 in one match. That's crazy."
Wozniacki said the match "slid out of my hands ... it's definitely disappointing."
Wozniacki's exit follows that of Angelique Kerber and Naomi Osaka in the first round, leaving the tournament without any of the trio of mothers and past champions who returned to the Grand Slam this year.
Jabeur and Wozniacki played their matches under the roof, on Rod Laver Arena and John Cain Arena, respectively, with rain causing the start of matches on the outside courts to be delayed for three hours. It cleared up, and the backlog of matches was limited.
Amanda Anisimova continued her comeback from a seven-month mental health break with a 6-2, 6-3 win over Nadia Podoroska. She will next play Paula Badosa, a 6-2, 6-3 winner over Anastasia Pavlyuchenkova.
Magdalena Frech won a second-set tiebreak to upset Caroline Garcia of France 6-4, 7-6 (2) and set up a third-round meeting with qualifier Anastasia Zakharova.
Elina Avanesyan upset world No. 8 Maria Sakkari 6-4, 6-4. The 21-year-old Russian will next face Ukraine's Marta Kostyuk, who beat former world No. 1 Elise Mertens 5-7, 6-1, 7-6 (6).
Ninth-seeded Barbora Krejcikova of Czechia secured a straight-sets win, firing off 30 winners and eight aces to ease past Germany's Tamara Korpatsch 6-2, 6-2. Qualifier Storm Hunter, world No. 1 in doubles, gave local fans more to cheer about when she beat Laura Siegemund 6-4, 3-6, 6-3 to continue her fairy-tale run at her home Grand Slam.
The Associated Press and Reuters contributed to this report.