Serena Williams has stormed into the quarter-finals of the Australian Open with a gritty 6-4 2-6 6-4 victory over Belarusian Aryna Sabalenka.
The match was a big test for Williams, who was up against one of the few players on the women's tour capable of matching her for power from behind the baseline.
The players went toe-to-toe in an even encounter, until Williams pounced late to break Sabalenka for the first time and take the opening set.
The roles were reversed at the start of the second, but with Sabalenka breaking Williams in her first two service games.
The American, who is chasing a record-equalling 24th Grand Slam title, clawed a break back, but was powerless in the face of Sabalenka's onslaught, as the seventh seed broke once more for a 4-1 lead, before sending the match into a decider.
With the pressure ramped up in the third, Sabalenka blinked first, making several errors on serve to hand Williams a 3-1 lead.
The Belarusian broke back and then levelled the set at 4-4 with a hold to love, but the pressure finally told, with Sabalenka serving to stay in the match trailing 5-4.
Sabalenka double-faulted to give Williams a 15-30 lead and netted a forehand to hand her two match points, conceding the match, after sending a forehand long.
Williams will face second seed Simona Halep in the last eight.
Osaka battles back from brink of defeat to reach quarter-finals
Naomi Osaka has saved two match points to battle back from the brink to reach the quarter-finals with a 4-6 6-4 7-5 victory over Garbine Muguruza.
The Japanese third seed chased the match from the start on Rod Laver Arena and played catch-up for most of the match.
She rallied from a set and a break down to level the engrossing contest.
Muguruza, a finalist at Melbourne Park in 2020, had conceded only 10 games to reach the fourth round.
The 27-year-old continued her rich vein of form to break for 5-3 in the decider and earned two match points in the following game.
Osaka saved both match points - the first with an ace - to turn the tide in the contest decisively and Muguruza exited the tournament a couple of games later, after failing to win a point in her final service.
Fans remained absent from Melbourne Park for a second day, because of the state of Victoria's coronavirus lockdown, and Osaka's victory was greeted with taped applause piped into the stadium.
"I'm tired right now, that was tough," says Osaka, who mixed 40 winners with 36 unforced errors over the contest.
"Today I feel like I was intimidated, she is playing well. I had to go within myself, I couldn't play short balls to her, because she'd put them away."
Next up for Osaka is an all-Asian quarter-final against unorthodox 35-year-old Hsieh Su-wei of Taiwan, who will play in the last eight of a Grand Slam for the first time.
"I'm not looking forward to it," Osaka adds. "Every time we have played it's three sets.
"It's fun when I'm not really angry. When I play her, I just have to expect everything."
Other fourth round women's draw results
Romanian second seed Simona Halep came from behind to beat Iga Swiatek 3-6 6-1 6-4 and avenge her defeat by the Polish teenager at last year's French Open.
Halep will play Serena Williams in the last eight.
Taiwan's Hsieh Su-wei reached the first Grand Slam quarter-final of her lengthy career when she shocked Czech 19th seed Marketa Vondrousova 6-4 6-2 on Margaret Court Arena.
At 35, Hsieh will be the oldest player to make a Grand Slam quarter-final debut in the open era when she plays Naomi Osaka later this week.