BIRMINGHAM, England -- Simona Halep has withdrawn from the Aegon Classic in Birmingham next week because of a left Achilles injury.

The No. 5-ranked Halep said Sunday she has "some fluid inside the tendon, so the doctor says that I have to rest for a few days" but that "it's nothing serious."

The grass-court event in Birmingham is a warm-up for Wimbledon, which starts June 27.