The Slovakian was reported to have felt ill after Tuesday's second stage, where he finished fourth in the sprint after 219 kilometres of racing. Wednesday morning brought a bout of vomiting for the former world champion.
Cyclingnews' reporter on the ground in Italy Stephen Farrand confirmed that Sagan is out of the race suffering from a fever in addition to his stomach problems.
The illness is the latest setback for Sagan after an unlucky start to his TotalEnergies tenure. His early season training was compromised after he caught COVID-19 for a second time in early January, while he looked off the pace at Omloop Het Nieuwsblad and Kuurne-Brussel-Kuurne last month.
Sagan was suffering from a sore throat and a fever last week, though he tested negative for COVID-19. It's unknown whether his current illness is a continuation of that or a new infection.
However, his absence from the remainder of Tirreno-Adriatico will mean that he's set to miss out on valuable racing preparation days for La Classicissima.
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Sagan was in competition for the in Sovicille on Tuesday after his TotalEnergies lead out hit the front in the final kilometres of the stage.
He hit the front after launching his sprint, but faded during the dash to the line, and was passed by eventual winner Tim Merlier (Alpecin-Fenix) in the closing metres. Young sprinters Olav Kooij (Jumbo-Visma) and Kaden Groves (BikeExchange-Jayco) also went past to take second and third.
"What can I say? It could have gone better but it could have gone worse," Sagan said, after the finish.
"They came up and over me from behind really strongly and with speed, and that made the difference."
Dani Ostanek is Senior News Writer at Cyclingnews, having joined in 2017 as a freelance contributor, later being hired full-time. Her favourite races include Strade Bianche, the Tour de France Femmes, Paris-Roubaix, and Tro-Bro Léon.
