World No 1 Naomi Osaka has pulled out of the Italian Open before Thursday's quarter-finals with injury just a week before the start of the French Open.
The 21-year-old withdrew because of a "pain in her right hand", organisers announced.
The Japanese star was due to meet Madrid Open champion and sixth seed Kiki Bertens for a place in the final four in Rome.
Osaka won twice on Thursday after the previous day's play was rained off, retaining the world No 1 ranking ahead of Roland Garros. She eased into the last eight in Rome with a 6-3, 6-3 win over Mihaela Buzarnescu.
Cheeky, @Naomi_Osaka_!
— wta (@WTA) May 16, 2019
The World No. 1 is a game from the quarterfinals with this clever play #ibi19 pic.twitter.com/tHwGbLEowz
Osaka beat the 29th-ranked Romanian in 78 minutes after earlier beating Slovak Dominika Cibulkova by the same scoreline in one hour and 42 minutes in the second round, as players doubled up after the previous day was washed out.
At the start of the day, Osaka had needed to make the quarter-finals to ensure Romanian Simona Halep could not swipe the No 1 ranking and with it top seeding in the French Open starting on May 26.
But Osaka's top spot was guaranteed when reigning Roland Garros champion Halep fell to Czech Marketa Vondrousova 2-6, 7-5, 6-3 in the second round.
"Of course, it's a relief [to be top seed at Roland Garros] because that definitely was a very big goal of mine."
Osaka, who broke through by winning the US Open last year and Australian Open this year, did not survive the second round in her two previous appearances in Rome.
Before this year Osaka had never made the last eight of any clay tournament, but has now also reached the semi-finals in Stuttgart and quarter-finals in Madrid as she warms up for the second grand slam tournament of the season in Paris.
