Top-ranked Iga Swiatek rallied from 4-1 down in the third set to escape with a narrow 6-4, 3-6, 6-4 win over 2022 runner-up Danielle Collins on Thursday and advance to the third round of the Australian Open.
Fifth-ranked Jessica Pegula, a quarterfinalist in each of the past three years, was beaten 6-4, 6-2 by Clara Burel. It was Pegula's earliest Grand Slam exit since she lost in the second round at Wimbledon in 2021.
Sloane Stephens, the US Open winner in 2017, took out No. 14 seed Daria Kasatkina 4-6, 6-3, 6-3 to reach the third round in Melbourne for the first time since 2019.
In a momentum-swinging opening match, Swiatek was on top after recovering an early break and leading by a set and a break before the American player rallied to take the second set and race to a 4-1 lead with two service breaks in the third.
Collins had three consecutive points to lead 5-2, but Swiatek absorbed the sustained pressure from her opponent's powerful groundstrokes until she reversed the momentum on a match-winning five-game roll.
"Oh my God, I don't even know," Swiatek said of how she managed to come back. "Honestly, I was on the airport already. But I wanted to fight to the end.
"I'm really proud of myself, because it wasn't easy."
Swiatek had two match points at 15-40 in the final game, but again Collins rallied, saving those and getting a game point with a trademark forehand winner deep to Swiatek's backhand side.
But a forehand long and a backhand wide from Collins gave Swiatek a third match point, and she made no mistake this time, flicking a backhand winner down the line to complete her victory after 3 hours, 14 minutes.
Collins announced soon after that 2024 would be her last season on tour.
In one of the tournament's toughest opening brackets, both players beat past Australian Open champions in the first round; Swiatek defeated 2020 champion Sofia Kenin and Collins overcame 2016 winner Angelique Kerber.
While Swiatek was doing her on-court TV interview, Collins was already en route to a news conference on site at Melbourne Park, in a much faster exit than usual.
"I lost 6-4 in the third to one of the best players in the world," Collins said. "And she played some great tennis. [I] left it all on the court."
A heavy rain shower at 3-3 in the opening set forced organizers to close the roof on Rod Laver Arena, creating a 25-minute delay.
After winning three of the next four games to wrap up the first set, Swiatek was down 5-1 and 40-15 in the second. She saved five set points before Collins clinched it, forcing a deciding third set.
Swiatek, who lost to Collins in the semifinals here two years ago, was again down two service breaks and needed some help.
"She played just perfectly, but it would be hard for anybody to keep that level," Swiatek said. "So I wanted to be ready when more mistakes are going to come from the other side. And I just wanted to push her, and I did that at the end."
The four-time major winner next faces No. 50-ranked Linda Noskova, who beat U.S. qualifier McCartney Kessler 6-3, 1-6, 6-4 in a match featuring two players in their Australian Open main draw debuts.
American No. 27 seed Emma Navarro recovered from a set down to beat 22-year-old Italian Elisabetta Cocciaretto 4-6, 6-3, 6-3, No. 12 Zheng Qinwen eliminated Katie Boulter 6-3, 6-3, and No. 19 Elina Svitolina wrapped up a 6-1, 6-3 win over Bulgaria's Viktoriya Tomova in just 65 minutes.
No. 11 Jelena Ostapenko took less than 20 minutes to win the opening set but then was made to battle by Ajla Tomljanovic before coming away with the 6-0, 3-6, 6-4 victory. No. 18 Victoria Azarenka also took over two hours before finally winning 6-4, 3-6, 6-2 against Clara Tauson.
The Associated Press and Reuters contributed to this report.