World No 1 and this year’s Australian Open champion Serena Williams on Wednesday pulled out of the upcoming Indian Wells Masters in California due to a knee injury.

Williams will also miss the Miami Open, which is scheduled to begin later this month. Her withdrawal will propel Germany’s Angelique Kerber to the No. 1 spot in the rankings.

The 23-time Grand Slam champion said, “I have not been able to train due to my knees.” However, she would statated that she would return to the court as soon as she could. Williams returned to the tournament in 2015 after a 14-year boycott owing to claims that she had suffered racist abuse at the venue.