The Giro d'Italia has lost seven riders including overall contender Steven Kruijswijk and the entire remaining Mitchelton-Scott team after rest day testing produced eight positive results for coronavirus.
Kruijswijk was one of two riders to test positive along with Australian sprinter Michael Matthews of Team Sunweb after a total of 571 tests were conducted on riders and staff since the end of stage nine on Sunday evening.
There were a further six positive tests involving team staff members, four of them within Mitchelton-Scott who have withdrawn from the race entirely as a result.
The Australian team had five riders – Jack Haig, Lucas Hamilton, Michael Hepburn, Damien Howson and Cameron Meyer – left in the race from their original eight after Simon Yates tested positive for the virus and withdrew on Saturday morning.
Eduardo Affini and Brent Bookwalter saw their races ended by crashes during the opening week.
Team manager Brent Copeland said: "Unfortunately we received the news on Monday evening that we have returned a number of positive COVID-19 results to members of our staff after our third round of tests in three days.
"As a social responsibility to our riders and staff, the peloton and the race organisation we have made the clear decision to withdraw from the Giro d'Italia."
Yates' withdrawal on Saturday had added to the nerves before Monday's full round of testing on the rest day, and the number of positives returned makes this the most significant outbreak at a single race since the season resumed in late July.
The exit of the luckless Kruijswijk means the Giro has now lost two of its pre-race favourites.
The 33-year-old Dutchman, who crashed while leading the 2016 edition during the final days, had targeted the Giro after a crash at the Criterium du Dauphine in August ruled him out of the Tour de France.
Jumbo-Visma said their team leader was not showing any symptoms or feeling unwell prior to receiving his positive test.
Kruijswijk said on the team website: "Within the team we take a lot of measures to avoid contamination.
"And I just feel fit. I can't believe I got it. It is a very big disappointment to get this news. It is a pity that I have to leave the Giro this way."
Similarly, Team Sunweb said in a statement that Matthews was showing no signs of the virus.
"He is currently asymptomatic, feels healthy and after receiving the results early this morning, he is now in quarantine," the statement said.
The other positive tests involved staff from the Ineos Grenadiers and AG2R La Mondiale.
The Giro resumes with Tuesday's 177km stage from Lanciano to Tortoreto, though the morning's announcement will increase fears it may not yet make it to Milan – where it is scheduled to end on October 25.
