Returning from a 15-month maternity break this year, Osaka had fallen in the first round at the Australian Open in January but looked set to breeze into the second round in Paris as the former world No 1 bombarded Bronzetti from the baseline.

She dominated the first set on a gusty Philippe Chatrier court to wrap it up in 28 minutes but her unforced errors rose steeply in the second, allowing Bronzetti to break in the crucial game at 5-4 and force a decider.

However, the 26-year-old Japanese player got back on track in the deciding set and had the opportunity to break for a 5-0 lead but appeared to implode as world No 67 Bronzetti clawed her way back into the contest.

Osaka pounced for a crucial break in the 11th game before finally clinching the back-and-forth battle.