Women’s world number one Serena Williams has withdrawn from the BNP Paribas Open in Indian Wells just before her semi-final match, due to a knee injury.

“A couple days ago at practice I really injured my knee. Today I was struggling just to even walk,” Williams said before leaving the court while the court side announcer clarified to spectators that she had withdrawn.

Serena Williams

The top seed did mention she would take part in next year’s Open, stating “It was really sad [getting injured] because I really felt four months ago I decided to start this journey to come back here at a place I’ve had so much success. And I can only promise to come back next year and play right here on this court in front of you guys.”

She was due to meet Simona Halep in the second semi-final, but came out after Jelena Jankovic beat Sabine Lisicki 3-6 6-3 6-1 in the first semi-final to make the brief announcement.

Williams was participating at her first BNP Paribas Open since 2001, a time she began her boycott of the tournament following the crowd’s angry reception toward older sister Venus who had also withdrawn at the semi-final stage where she was to meet with Serena.