World No 2 Maria Sharapova has blamed "physical problems" after she was forced to pull out of the Rome Open.
Sharapova, who won her second Rome title last year, was scheduled to face Sara Errani in the Friday's quarter-final.
Errani now gets a bye to the last four after Sharapova revealed she would not take to the court.
"I've a lot on my schedule and they all mean a lot for me and obviously with the French Open coming up it is important to make smart decisions," said Sharapova, who was runner-up to Serena Williams in Madrid last weekend.
Sharapova said she felt physically under-par during her win over Sloane Stephens on Thursday, but that she had also been "a bit off" in Madrid last week.
"You could see it in my energy last night," she said. "I was already a bit off in Madrid and played through it and it came back last night and I got sick again.
"It's not smart to again compete two or three rounds to win the tournament and with Paris starting next week."
World No 6 Errani will now take on Viktoria Azarenka for a place in the final after she defeated Sam Stosur.
The Belarusian star got the better of her opponent in three-sets, 6-4 1-6 6-3 to advance through to the last four in an hour and 58 minutes.
The world No 3 also took her overall record to 8-0 in head-to-head meetings against the Australian ninth-seed.