Serena Williams, who was making her return to Indian Wells after deciding to end her 14-year boycott, has pulled out of the hardcourt tournament with a right knee injury.

The world No.1’s withdrawal means third seed Simona Halep advances to Sunday’s final, where she will face Jelena Jankovic.

Williams made the announcement on her Twitter account on Friday night, saying she was disappointed she couldn’t finish a journey that started late last year with the decision to end her boycott.

“4 months ago I began a journey to play Indian Wells and it was amazing,” Williams said. “I never dreamed I could do it. But I would not have been able to do this without my fans.

“Though it ended early due to injury this year, I have to say I cannot wait to try again next year. Thanks everyone. I love you so much!”

She did not go into detail about the injury.

Williams had been competing at the Californian event for the first time since her self-imposed exile began after being heckled and booed when she won the 2001 final against Kim Clijsters. She also claimed the Indian Wells title in 1999.

The announcement comes as a shock to tennis fans. Williams showed no signs of being hurt in her three previous matches and said several times over the past week she felt comfortable again playing at the tournament.

The injury also means Williams could miss next week’s hardcourt tournament in Miami.

2010 champion Jankovic advanced to the final with a 3-6 6-3 6-1 win on Friday night over Sabine Lisicki of Germany.