Kerber and Williams entered the tournament facing a battle for World No.1, with the American needing to reach at least the semifinals to hold on to the top spot. But the race to the top took another twist as Williams announced her withdrawal on Tuesday before the start of play at Indian Wells:
"Sadly, I have to withdraw from the BNP Paribas Open in Indian Wells and the Miami Open," Williams said in a statement. "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."
As a result, Kerber is projected to return to World No.1 when the new WTA rankings are released on Monday, March 20 after Indian Wells and will hold on to the spot through at least April 2, which will take her career total to 22 weeks at No.1.
The German first rose to the World No.1 ranking on September 12, 2016 after winning her second Grand Slam at the US Open. Kerber became the second German woman to reach the milestone since the computer rankings were introduced in 1975, and the first since Stefanie Graf. The then-28-year-old also became the oldest player to make her debut at No.1, a record previously held by Jennifer Capriati, who was 25 years, 200 days when she reached No.1 in October 2001.