World number one Naomi Osaka crashed out of the Dubai Duty Free Tennis Championships after losing in straight sets to France’s Kristina Mladenovic.

Osaka, who announced a surprise split from her coach Sascha Bajin, earlier this month, was beaten 6-3 6-3 in the second round, having received a first-round bye as the top seed.

The 21-year-old, who won the Australian Open last month and the US Open last year, gave no reasons for ending her successful partnership with Bajin.

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