Cape Town - Alexander Zverev says he is worried about his current mental state, admitting he was 'completely out of it' as he fell to defeat in the first round of Basel.
The German world No 7 was a semi-finalist last year, but sank to a disappointing straight sets loss to American Taylor Fritz on Tuesday.
Speaking after the match, it is clear that Zverev is struggling.
"The way I played today, in my current mental state, I'm not going to beat anybody," Zverev said.
"I'm very disappointed but it's more about myself than the result.
"Normally I really enjoy it on court, the tough moments, the fighting.
"But today I was completely out of it. I may go home for a few days and clear my mind. I'll try to do well in Paris and hopefully make it to London."
Zverev's place at the ATP Finals London, where he is the reigning champion, is now in real danger, and he admits he is struggling to explain the defeat in Basel.
"I was completely flat for some reason," he said. "I was tired and not focused at all. It was a weird feeling."
- TeamTalk Media