Defending champion Elina Svitolina was among those to progress at the Dubai Tennis Championships as Naomi Osaka was the only truly high-profile name to crash out on Tuesday.

Osaka, who announced last week she had split from coach Sascha Bajin, was stunned by Kristina Mladenovic in her first match as world number one, losing in straight sets in just over an hour after a shoddy display.

But the majority of the other seeds in the draw progressed, including Svitolina and Simona Halep, who breezed past Eugenie Bouchard.

Petra Kvitova and Angelique Kerber both battled back from early deficits, while Karolina Pliskova beat Dominika Cibulkova, with Garbine Muguruza easing to victory over Zheng Saisai. Aryna Sabalenka thrashed Ivana Jorovic.

Some seeds did join Osaka in exiting, though, with Kiki Bertens departing after defeat in a third-set tie-break to Viktoria Kuzmova, while Caroline Garcia went down to Jennifer Brady in straight sets.

MOTIVATED BY HISTORY

Svitolina has triumphed in Dubai in the last two years, matching the back-to-back achievements of Justine Henin (twice) and Venus Williams, and could become the first woman to win three in a row.

But the Ukrainian did not have it all her own way for a time on Tuesday, trailing to an early Ons Jabeur break before rallying and seeing her opponent bow out with injury.

And Svitolina is very aware of the potential of a groundbreaking achievement, later revealing that she was motivated to recover due to that very opportunity.

"It's definitely a big motivation for me," she said. "When I was 0-2 down, I told myself, 'Come on, you are here to make history in this tournament'."

OSAKA NOT WORRIED

Osaka looked a shadow of her usual self as she was beaten in her first match since the Australian Open.

The top seed never got going and, despite breaking several times in the second set, found herself unable to hold serve as Mladenovic claimed a famous victory.

Rising star Osaka does not believe the defeat provides cause for concern, though, explaining: "The Australian Open was not even a month ago. This was just one match.

"I feel like, even if I don't win any matches for the rest of the year, I wouldn't say I'm concerned. I think I'm pretty young. I still feel like I have a lot to learn."

STARS WORKED HARD

Kvitova and Kerber might have avoided the embarrassment of Osaka's defeat, but they were far from comfortable in their own victories.

Second seed Kvitova lost the opening set to Katerina Siniakova before staging a recovery to win 6-7 (3-7) 6-4 6-4.

Meanwhile, Kerber was two breaks down to Dalila Jakupovic in the first set, trailing 5-1 and saving two set points. A stunning response set up a 7-6 (7-4) 6-3 success.