BEIJING -- Top-ranked Garbine Muguruza retired from her opening match at the China Open with a cold Monday.
Muguruza dropped the first set 6-2 and was trailing 2-0 against Barbora Strycova when she decided to stop.
"I couldn't perform today," said the Spaniard, who said she picked up a virus at the Wuhan Open last week but wanted to try to play despite her illness. "I don't want to retire before the tournament starts for me."
"It was a tough day," Stephens said. "There's not really much to say about. Obviously not a great match, so just forget about it and try to move on."
Top-ranked Rafael Nadal will open against Lucas Pouille on Tuesday. The Frenchman beat Nadal in their previous meeting last year.