INDIAN WELLS, Calif. (AP) Serena Williams withdrew from the BNP Paribas Open that begins Wednesday because of a left knee injury, leaving the desert tournament without the world's top-ranked women's player.
The withdrawal also cost Williams a chance to retain her top ranking.
Angelique Kerber, a two-time semifinalist and now the highest-seeded woman in the event, will supplant Williams at No. 1 after Indian Wells. Williams needed to reach the semifinals to retain the top spot.
Williams said Tuesday in a statement released through the tournament that she also won't play the Miami Open, which begins March 21 and isn't far from her Florida base.
She has been idle since beating sister Venus Williams for the Australian Open title on Jan. 29. Her only other tournament this year was in Auckland, New Zealand, where she lost in the round of 16.
''Sadly, I have to withdraw from the BNP Paribas Open in Indian Wells and the Miami Open,'' Williams said. ''I have not been able to train due to my knees and am disappointed I cannot be there. I will keep moving forward and continue to be positive. I look forward to being back as soon as I can.''
Williams is a two-time winner at Indian Wells, where she returned in 2015 after a lengthy boycott. She withdrew before her semifinal match that year with a sprained right knee, and lost to Victoria Azarenka in straight sets in last year's final.
Venus Williams, seeded 12th, returns for the second straight year, having ended her own boycott of the event last year.
Also missing on the women's side is Azarenka, who gave birth to a son in December; two-time Wimbledon champion Petra Kvitova after being attacked in a home invasion late last year; and Maria Sharapova, who is set to return in late April after serving a 15-month doping ban.