Defending champion Ons Jabeur said on Monday she had withdrawn from the Madrid Open with a calf injury after retiring from the Stuttgart Open at the weekend.

The Tunisian world number four retired after three games against Iga Swiatek in the Stuttgart Open semi-final, where she was injured during the last point of the first game on Saturday.

"Further to many medical exams done, it shows that I have a small tear in my calf and I will need more time to recover," the 28-year-old Jabeur said on Instagram.

"I'm sad to announce that I won't be able to compete and defend my title this year at the Madrid Open. I would like to wish everyone and the tournament a great event."

Jabeur, who was on a seven-match winning run after recovering from injury and surgery earlier this year, was to face Romania's Ana Bogdan or Hungary's Anna Bondar in the second round of the clay tournament in Madrid.

The Madrid Open will be played from Tuesday through May 7.