Serena Williams retired from her Indian Wells match against Garbine Muguruza citing “extreme dizziness and extreme fatigue”.
Muguruza was winning 6-3 1-0 when Williams was forced to withdraw from the third round meeting.
Williams had gone 3-0 ahead but after losing six consecutive games, she called for the trainer. She emerged for the second set but it was short lived.
"Before the match, I did not feel great and then it just got worse with every second - extreme dizziness and extreme fatigue," 23-time Grand Slam champion Williams said.
"By the score it might have looked like I started well, but I was not feeling at all well physically. I will focus on getting better and start preparing for Miami."
In the men's draw, Roger Federer and Rafael Nadal cruised into the round of 32.
Nadal thrashed Jared Donaldson 6-1 6-1 and Federer beat Peter Gojowczyk 6-1 7-5.
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