A "sick" Alexander Zverev said he "should not have played" after he lost in the French Open fourth round to Italian teenager Jannik Sinner.

The 23-year-old was up to date with his tournament-organised Covid-19 tests, with his last one on 29 September.

But a French Tennis Federation (FFT) statement said: "He did not consult the tournament doctors before his match."

Zverev told reporters he had a temperature of 38 Celsius during the night after his previous match against Marco Cecchinato on Friday.

"I'm completely sick. I can't really breathe, as you can hear by my voice. I had fever as well," the US Open finalist said in his post-match news conference on Sunday.

"I'm not in the best physical state. I warmed up today. I should not have played."

A statement from the FFT said Zverev's previous coronavirus test was negative, with the result coming through on 30 September.

"Today he received a reminder for his next test, to be carried out within five days of the previous results," the FFT said.

Analysis

BBC tennis correspondent Russell Fuller at Roland Garros

At last month's US Open, players were not allowed to board the bus to Flushing Meadows until they had passed a temperature test and completed a health questionnaire.

The rules are not as stringent at the French Open, although the players are being tested for Covid-19 every five days.

The question, therefore, for all of us here, is what should we do if feeling unwell?

The health and safety protocol issued to all accredited people calls for a "sense of duty and responsibility".

It says: "Anyone showing symptoms - fever, dry cough, breathing difficulties, muscle pains, severe fatigue, loss of taste and/or smell, diarrhoea - must adopt a responsible attitude and not attend the stadium."

Debutant Sinner emulates Nadal

Zverev's illness overshadowed an impressive performance from world number 75 Sinner, considered one of the rising talents in the men's game.

Both Sinner and Zverev lost five-set matches at the US Open from two sets up - Sinner in the first round against Karen Khachanov, while Zverev did so in agonising fashion in the final against Dominic Thiem.

Zverev threatened a comeback when he took the third set but the 19-year-old was the more aggressive player throughout, hitting 39 winners to the sixth seed's 20.

After regrouping in the fourth set, Sinner consolidated an early break and wrong-footed Zverev with some smart net play to close out victory in just over three hours.

He is the first man since Rafael Nadal in 2005 to reach the French Open quarter-finals in his main draw debut, and the youngest man to reach the quarter-finals at a Grand Slam since Novak Djokovic in 2006.

"It's great to reach the quarter-finals here. I am quite calm, so even if inside I'm very happy, I don't show that so much," said Sinner, who faces Nadal in the quarter-finals.

"But there is still a lot of work to do. Physically, technically, everything. It's a long way."