BEIJING, China - Barbora Strycova progressed to the second round of the China Open after World No.1 Garbiñe Muguruza retired when trailing 6-1, 2-0 on Monday.
The Spaniard, 24 next Sunday, was broken in the first game of her third tournament since topping the rankings, and was unable to recover. She lost her service twice more in losing the first set in just 27 minutes, making 16 unforced errors.
Muguruza then called for the trainer after being broken again in her opening service game of the second set to trail 2-0, and retired for the fifth time in 2017. She has now won four of her seven matches as World No.1.
"It's very tough, I got a virus in Wuhan," the 2015 China Open winner said afterwards. "I couldn't perform today.
"It's the easy way to think: 'don't go on the court'. I want to feel like giving the last chance, going on the court, just hit [a] few balls, see how I'm going to feel, try to turn things around.
"I don't want to retire before the tournament starts."
Muguruza had reached the quarterfinal in Wuhan and semifinal in Tokyo in her two tournaments since being confirmed as World No.1 last month but struggled from the start in Beijing.
She held a 3-2 winning record against her 31-year-old opponent, but had lost two of their last three meetings, at the Australian Open last year and in Eastbourne earlier this year.
"It's never easy to win this way," Strycova said. "But it happened, I am in the second round. That is how it is and sometimes things happen that way. I just kept fighting and was happy I won those three games at the beginning because that was a turning point."
Strycova continued her good recent form against Muguruza to move into the second round of the event for just the second time - where she will face Julia Goerges in the second round.
"She is a very tough opponent," Strycova added of her next match-up. "We always have big battles against each other. I will give my best."