Garbine Muguruza blamed low energy levels for her second-round exit from Wimbledon at the hands of Jana Cepelova on Thursday.
Muguruza, the French Open champion and 2015 Wimbledon finalist, was beaten 6-3 6-2 by a player ranked 122 places below her.
The second seed was taken to three sets by Camila Giorgi in the first round and an error-strewn display resulted in defeat in less than one hour on Court No.1.
Muguruza admitted to feeling lethargic on court, while also being troubled by illness.
"I think my energy was missing a little bit today. From yesterday I felt already a little bit tired, and today during the match, and after the match. It's a tough day. I feel empty a little bit, and I start to be sick," said the Spaniard.
"I think she played great, with no fear. She was trying a lot of stuff that was working. My energy was not really there.
"I was trying, but didn't work at all. I just have to recover a little bit and, you know, get my energy back, then be good again.
"I was just very clear it was going to be a rough tournament for me after winning a grand slam and coming here. Everybody, you know, like, looking at me. But there is not any drama."