Doha - World No 2 Simona Halep pulled out of the Qatar Open on Friday with a recurrence of the foot injury which had forced out of the game since the Australian Open.
A "frustrated" Halep made her announcement just after winning her quarter-final against American teenage qualifier, Catherine Bellis, 6-0 6-4.
"I withdraw because I cannot play anymore and it's going to be dangerous if I force it," she told reporters.
She said it was the same problem that she had in Melbourne, where she lost the Australian Open final to Caroline Wozniacki.
"Today it was worse, and that's why I took this decision. It's not easy, but I talked to my doctor. He said that I didn't have enough time to recover.
"The MRI shows that I have fluid and also tendonitis at the fourth toe.
"So I have just to take care of it and thinking about the health first."
The Romanian was making her return to competitive action in Doha after a lay-off of more than two weeks, which had also seen her drop out of a Fed Cup tie last weekend.
She spoke earlier in the week in Doha that her right foot and ankle were painful but would take the Qatar tournament "day-by-day".
Halep added that she would not return to action until Indian Wells at the earliest, which begins next month.
Results from the WTA Qatar Open in Doha on Friday (x denotes seeding):
Caroline Wozniacki (DEN x1) bt Angelique Kerber (GER x8) 7-6 (7/4), 1-6, 6-3
Garbine Muguruza (ESP x4) bt Caroline Garcia (FRA x7) 3-6, 6-1, 6-4
Simona Halep (ROM x2) bt Catherine Bellis (USA) 6-0, 6-4