Team Sky rider Richie Porte has been forced to abandon Tirreno-Adriatico ahead of stage five due to illness.
The Australian had been fourth in the general classification, 34 seconds down on leader Michal Kwiatkowski, but became ill overnight and was unable to take the start line in Amatrice on Sunday morning.
The news came hours after fellow Team Sky rider Geraint Thomas withdrew from Paris-Nice following a heavy crash 5km from the finish of stage seven.
Team Sky doctor Alan Farrell said: "Unfortunately, due to illness which occurred overnight, it has been decided that Richie is too unwell to start the race this morning. We expect him to recover quickly and hope to have him back in training within the next 48 hours.
"He is really disappointed but recognises that this is the best course of action to prepare him for his upcoming races. He is looking forward to the Tour of Catalunya next week."
Paris-Nice concludes with an eighth stage around Nice on Sunday, while Tirreno-Adriatico continues with a fifth stage to Guardiagrele.