World number two Aryna Sabalenka fixed her early-season serving horrors to rally from a set down and power into the Australian Open second round Tuesday.

The second seed from Belarus came into the season-opening Grand Slam low on confidence after self-destructing at two warm-up tournaments where her serve left her distraught.

It got so bad against world number 93 Rebecca Peterson in Adelaide that she was reduced to sending deliveries underarm, at one point breaking down in tears.

Across those two defeats, she threw down 39 double faults.

She reduced the count to 12 against Storm Sanders on Rod Laver Arena to win 5-7, 6-3, 6-2, but with four in her first two service games it appeared she was in for another miserable night.

Sabalenka, though, kept her cool and finally found her range to stay in the match and the tournament.

"The start of the season was not great and really happy I got this win," she said.

"I stopped thinking too much and just tried to play tennis. She was a tough opponent so very happy."

Sabalenka, enjoying her highest-ever seeding at the Australian Open, sent down her first double fault on her opening serve with Sanders breaking to take an immediate advantage.

The Belarussian was dangerous when the ball was in play but her confidence was down and she made three more double faults on the next game to slump 2-1 behind.

Sensing her chance, Sanders comfortably held and while Sabalenka managed to avoid more double faults on her next service game her delivery lacked potency.

But she stayed in the hunt by breaking Sanders and then holding for the first time to be 3-4.

Another hold helped her confidence, but the jitters returned and two more double faults allowed Sanders another break for 6-5 and she made no mistake this time to take the set.

Yet more double faults allowed the Australian to move 3-1 clear in the second set, but 23-year-old Sabalenka refused to go quietly.

Her first ace of the match helped her through a tough seventh game for 4-3 and she then broke again and took the set, pumping her fists in celebration.

Sanders' confidence was sapped and Sabalenka, a fourth round loser last year to Serena Williams, made no more mistakes and raced to victory.