Atalanta manager Gian Piero Gasperini said he was ill before his side's Champions League round-of-16 second-leg clash in Valencia and that later tests showed he had contracted coronavirus.
The Serie A side are based in Bergamo, which has been the worst-hit region in terms of coronavirus deaths in Italy, and a leading doctor from the area said their first-leg match with Valencia at the San Siro stadium in Milan had accelerated the spread.
"The night before the match in Valencia I was ill," Gasperini told La Gazetta dello Sport. "The afternoon of the match, I was even worse.
"On the bench, I was feeling awful. It was March 10. The two previous nights in Zigonia [Bergamo], I didn't sleep much.
"I wasn't feverish, but I felt so worn down as if I'd had was 40C (104F). Every two minutes, I'd hear an ambulance go by. There's a hospital nearby. It felt like wartime.
"At night, I'd think: 'if I go in there, what will happen to me?' 'I can't go now, I have too much to do.'
"I'd say it jokingly, for exercise. But I would really think it."
Valencia issued a statement on Sunday expressing surprise that Gasperini would have managed the match given that it was being played behind closed doors due to the spreading of coronavirus in Italy and Europe at the time.
"Following comments made by the Atalanta manager, Gian Piero Gasperini, in the Italian media on Sunday, Valencia CF want to express their surprise at the fact the coach of a rival team in the Champions League would admit that, on the day before the game played on March 10 at Mestalla, he was aware that he, at the very least, was suffering from symptoms compatible with coronavirus and without taking any precautionary measures. He put in risk, if it was the case (that he had coronavirus), a number of people during his stay in Valencia.
"Remember that this game was played behind closed doors and with strict safety measures in place to prevent the risk of contagion of COVID-19, especially given the presence of people from an area (Bergamo) that had already been quantified as high risk."
On March 10, the Italian government ordered a total lockdown and that was when football was stopped in the country. In the subsequent days, Gasperini said he began to feel better.
"On Saturday 14 [March], I did a type of extreme workout I hadn't done for years," he added. "An hour on the running machine -- more than 10km.
"I felt fine, strong. The worst had passed. I stayed in Zingonia for three weeks. Later I went to Turin, always respecting social distancing measures with my wife and children.
"Despite not having a fever, I did the test. Ten days ago, the tests confirmed I had had COVID-19. I have the antibodies, but that does not mean I'm immune."
Serie A recently announced top-flight football would return in the country from June 20.
The Champions League was stopped midway through the round-of-16 second-leg ties with Atalanta having qualified for the quarterifinals for the first time, and Gasperini said the pain in Bergamo would drive his side on in the competition.