Serena Williams has withdrawn from the Miami Open due to an injury to her left knee, tournament organisers have confirmed.
Williams came through her opening match against Rebecca Peterson in three sets, but she will no longer take to the court to face Wang Qiang on Sunday.
It is the second successive tournament Williams has been forced to pull out of. At the Indian Wells Open earlier this month, she retired during her match with Garbine Muguruza due to a viral illness.
"I am disappointed to withdraw from the Miami Open due to a left knee injury," Williams said in a statement.
"It was an amazing experience to play at the Hard Rock Stadium this year and [I] would like to thank the Miami Open for putting on an amazing event.
"I hope to be back next year to play at this one-of-a-kind tournament in front of the incredible fans here in Miami."
Williams' withdrawal means she has still completed only one event so far in 2019 – the Australian Open, in which she was beaten by Karolina Pliskova in the quarter-finals.