Serena pulls out of Indian Wells and Miami with knee injury

World No. 1 Serena Williams has pulled out of the two upcoming WTA Premier Madatory tournaments in Indian Wells and Miami due to a left knee injury.

"Sadly, I have to withdraw from the BNP Paribas Open in Indian Wells and the Miami Open," Williams said in a statement Tuesday. "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."

Because she will not defend her Indian Wells finalist points from last year - when she lost the title match to Victoria Azarenka - she will once again lose her top ranking to Angelique Kerber. She'll lose further ground in the rankings after Miami, where she lost in the Round of 16 a year ago.

Williams had retaken No. 1 from Kerber with her Australian Open championship in January. She's yet to play a match since then.

Williams returned to Indian Wells in 2015 after a 14-year boycott, and has gone 9-1 at the tournament since then (she pulled out of the semifinals with an injury her first year back). She's won the Miami Open a record eight times.

The Indian Wells draw will be reshuffled, with Kerber taking over the top seed.