BRISBANE, Australia (AFP) — World No. 1 Aryna Sabalenka sent an Australian Open warning as she beat Madison Keys on Friday in Brisbane in a repeat of last year’s Melbourne final.

Keys stunned Sabalenka nearly 12 months ago but the Belarusian took revenge on the American with a statement 6-3, 6-3 victory to reach the semifinals.

Keys was playing less than 24 hours after her marathon three-hour win over Russia’s Diana Shnaider and had heavy strapping on her thigh.

She turned in an uncharacteristically error-strewn performance and struggled on serve as Sabalenka struck a series of superb returns.

Sabalenka, aiming for her third Melbourne title in four years when the Australian Open begins on 18 January, said the Brisbane tournament was helping her find form ahead of the first major of the year.

“I’m just trying to bring on court things I have been working on the pre-season, such as coming to the net,” she said.

“I was working on my serve and it seems that it’s working a little bit better.”

“I’m just trying to get some matches, get some wins, get the rhythm going again.”

Sabalenka will play Czech surprise package Karolina Muchova in the last four after the 11th seed held her nerve to see off world number five Elena Rybakina 6-2, 2-6, 6-4.

Muchova raced through the first set against an out-of-sorts Rybakina, who eventually found some rhythm to claim the second.