German Alexander Zverev has said that he played with a fever and breathing difficulties during his fourth-round French Open defeat to Italian teenager Jannik Sinner, raising questions about the Covid-19 protocols at the claycourt Grand Slam, according to Reuters.

Zverev appeared to be in discomfort and was seen coughing on court during the match against Sinner and called for the doctor and trainer. He kept pointing at his throat and later took a pill.

The German player later said he had been ill since his third-round win against Italian Marco Cecchinato on Friday and had a body temperature of 38 degrees celsius.

“It was nothing wrong but I am completely sick after the match with Cecchinato in the night. Yeah, what can I say? I'm completely sick,” said Zverev, wearing a mask as usual during his virtual post-match news conference.