Sabalenka, 26, appeared certain to charge into a third consecutive Open semi-final when she cantered through the first set at Rod Laver Arena on Tuesday night.
But Pavlyuchenkova hit back to claim the second set - the first Sabalenka has lost at Melbourne Park since the 2023 final against Elena Rybakina - and force the match to a decider.
A shaky Sabalenka managed to hold her nerve to prevail 6-2 2-6 6-3 in an hour and 53 minutes and tee up a semi-final against 11th seed Paula Badosa, who upset third seed Coco Gauff 7-5 6-4 earlier on Tuesday.
"Honestly I was just praying today," Sabalenka said after her 19th consecutive win at Melbourne Park, as she attempts to become the first woman since Martina Hingis (1997-1999) to win three titles on the spin.
Aryna Sabalenka prayed and toughed it out in her win over Anastasia Pavlyuchenkova. (Lukas Coch/AAP PHOTOS)
"I was just praying, trying to put the ball back in these tough conditions - we were both just trying to put the ball back.
"She plays amazing tennis, very aggressive. I'm just happy I was able to somehow magically win this match.
"Sometimes maybe it's good to have these tough battles, to go through it, to be tougher for these last matches of the tournament ... I cannot wait to play against Paula."
ğ�Ÿğ�Ÿµ-ğ�Ÿ¬ at Melbourne Park ğŸ˜�— #AusOpen (@AustralianOpen) Aryna Sabalenka's title defence is STILL ALIVE as she battles past Pavlyuchenkova's challenge 6-2 2-6 6-3. #AusOpen • #AO2025 pic.twitter.com/AyJnkxpyo8January 21, 2025
Sabalenka took 31 minutes to wrap up the first set, letting out a "let's go" and fist pumping after breaking Pavlyuchenkova to seal it.
But 27th seed Pavlyuchenkova, 33, wouldn't lie down.
Instead she broke the Belarusian and went toe-to-toe with Sabalenka from the baseline in the second set.
As the set progressed, the Russian just went from strength to strength, at times leaving Sabalenka stunned with brutally powerful winners.
Anastasia Pavlyuchenkova was gallant in her three-set loss to Sabalenka. (Joel Carrett/AAP PHOTOS)
Pavlyuchenkova raced to a double break and 4-1 lead as Sabalenka cut an increasingly frustrated figure.
The pair again traded breaks and Pavlyuchenkova earned a 5-2 lead and chance to serve for the second set.
She claimed the set with aplomb and broke Sabalenka at the start of the deciding set.
The pair twice traded breaks before Sabalenka seized control.
The Belarusian broke Pavlyuchenkova at 4-3 then rediscovered her ruthless edge to serve out the match.
