Naomi Osaka loses to Kristina Mladenovic in first game since dumping her coach

World No 1 Naomi Osaka has been beaten in her opening match at the Dubai Duty Free Tennis Championships, losing to France's Kristina Mladenovic 6-3 6-3 after winning last month's Australian Open.

Japan's Osaka, who parted ways with coach Sascha Bajin last weekfollowing her victory in Melbourne, struggled with her service game on Tuesday (Wednesday NZT).

She won 48 per cent of her first serve points and made 25 unforced errors, folding in just over an hour.

Mladenovic hit three fewer winners than Osaka's 19, but made nine unforced errors and converted seven of the 10 break point opportunities she carved out en route to registering her first career victory over a reigning world No 1.

"It means a lot, honestly," Mladenovic said after the match.