2018 French Open Women's Singles - Serena Williams pulls out before she is due to play Maria Sharapova

Serena Williams has pulled out of the French Open before her fourth-round match with Maria Sharapova.

The 36-year-old will explain the reason for her withdrawal in a news conference, with a suggestion that she has an arm injury.

The 23-time Grand Slam winner recently returned to tennis after giving birth to her first child.

She looked in good form in her opening matches, dropping only one set en route to the last 16.