Australian Open champion Aryna Sabalenka fought back from a set down to end the title defence of Jelena Ostapenko at the Dubai Tennis Championships.

Sabalenka, playing in her first event since claiming a maiden grand slam title in Melbourne, recovered from falling behind in style to win 2-6 6-1 6-1 on Wednesday.

Ostapenko won the tournament last year and looked to be in with a chance of extending her winning streak in Dubai to seven matches.

But Sabalenka launched a strong recovery to reach the quarter-finals and extend a stunning run to start the season to 13 consecutive wins.

The second seed tightened up her game in the second and third sets and will face either Petra Kvitova or Barbora Krejcikova in the last eight.

Sabalenka had been broken three times by Ostapenko in the opening set, but she only had to fend off one break point from there.

"In the first set, she played unbelievable tennis and I couldn't do anything," Sabalenka said.

"I was looking at my team asking like, 'What can I do?', but somehow, I turned around this game and started playing really incredible tennis. 

"She plays really fast, deep balls, and I tried to stay super low, stay focused, and try to put more balls in than she did. I'm so happy that I did it."

A lower back injury for Wimbledon champion Elena Rybakina robbed supporters of what had looked like being a thrilling matchup against Coco Gauff.

The withdrawal of Rybakina meant Gauff progressed via a walkover and will face fellow American Madison Keys next.

Keys and Gauff have played twice before, winning one match apiece.

It was Gauff who won their most recent encounter in the third round of the US Open last year.

Top seed Iga Swiatek had earlier booked her place in the last eight, with the Pole's latest dominant showing in Dubai earning praise on social media from Andy Murray.

And news followed that Karolina Pliskova, her semi-final opponent, had been forced to withdraw.

Swiatek benefited from a walkover in the quarter-finals en route to winning the Qatar Open last week and is now only two wins away from another title.