MELBOURNE, Australia — Aryna Sabalenka, the world No. 1 and two-time champion at the Australian Open, survived a major scare against Anastasia Pavlyuchenkova to advance to the semifinals.

Sabalenka was twice a break down in the deciding set, but recovered to claim a 6-2, 2-6, 6-3 victory and a 19th straight win at Melbourne Park. With both players winning just over 60 percent of their first-serve points for the match, it was second-serve points that made the difference. Sabalenka won that battle in the first and third sets; Pavlyuchenkova won it in the second.

She will play her good friend Paula Badosa in the Thursday’s semifinal, in another match in which she will be a clear favorite, but this was another performance to chip away at Sabalenka’s diminishing aura.

That may sound like a strange thing to say about a player looking for her third title here in a row, but so far Sabalenka has not been anything like as formidable as she was last year. She’s winning matches by force of will a lot of the time, and opponents know they will get her chances against her at the moment.

Sabalenka had struggled to find her best level throughout this tournament, with every match bar her fourth round against Mirra Andreeva featuring ups and downs and numerous dropped service games.

Still, she hadn’t dropped a set. When she took the opener against No. 27 seed Pavlyuchenkova  6-2, it looked like being a relatively straightforward evening for the world No. 1.

Instead, the momentum of the match shifted early in the second set, when Pavlyuchenkova broke for 2-1. It was the first of five successive service games that Sabalenka lost, seemingly struggling with her ball toss on a gusty Melbourne night. Her stress on serve bled into the rest of her game and Pavlyuchenkova took advantage.

Pavlyuchenkova also raised her level and her aggression. She was ripping into her returns, keeping Sabalanka — so used to being the protagonist — on the back foot. The tactic was particularly effective because of Pavlyuchenkova’s confidence at the net, which left her with some easy putaways and added to Sabalenka’s discomfort. One improvised volley winner behind a return illustrated the challenge Sabalenka was facing to hold serve.

Sabalenka was desperately trying to lift herself through adversity, and at the start of the third set she was roaring in celebration at any point she won. She was twice a break down, but broke back immediately on both occasions, which halted Pavlyuchenkova’s momentum and the growing sense that this was going to be her night.

Sabalenka then locked down her service games, holding to love twice in a row to end the run of five consecutive breaks for Pavlyuchenkova. The Russian’s own level dropped, and she gave up a shaky service game that saw Sabalenka break for 5-3, to leave herself serving for the match.

With one last roar of celebration, Sabalenka was into yet another Grand Slam semifinal, the 10th time she’s reached this stage at her last 11 majors.

(Hannah Peters / Getty Images)