Naomi Osaka has withdrawn from the Italian Open in Rome to rest an Achilles injury ahead of the French Open, the WTA said on Monday.

The four-time Grand Slam champion suffered the injury in her opening match in Madrid earlier this month, before struggling in a second-round loss to Sara Sorribes Tormo.

"Unfortunately I'm going to have to withdraw from Rome as the injury which I picked up last week in Madrid hasn't healed yet," the Japanese star said in a statement.

"It's an Achilles injury so I need to be careful, especially in advance of Roland Garros."

The former world number one has never reached the final of a clay-court tournament, but will be hoping to put that record straight at the French Open which starts on May 22.

Osaka, currently ranked 38th, has shown signs of a return to form this year.

The 24-year-old reached the Miami Open final, where she lost to world number one Iga Swiatek, in April.

She has been replaced in the Rome draw by Spain's Nuria Parrizas Dias.