Kerber moved atop the rankings Monday. That's about six months after she originally ascended to No. 1 for the first time, overtaking Williams by winning the US Open.
That ended Williams' run of 186 consecutive weeks at the top.
Williams reclaimed the No. 1 ranking in late January when she won the Australian Open for her 23rd Grand Slam title.
But the American has not played since then because of an injured left knee. She sat out the Indian Wells tournament that ended Sunday and will miss the Miami Open that begins Tuesday.