The Jumbo-Visma and Mitchelton-Scott teams have withdrawn from the Giro d’Italia after six positive results in the latest round of Covid-19 testing.

General classification contender Steven Kruijswijk, who rides for Jumbo, tested positive as did four staff members of the Australian Mitchelton-Scott team.

Out of 571 tests, Team Sunweb’s Michael Matthews also tested positive.

Mitchelton-Scott’s British rider Simon Yates, another pre-race favourite, tested positive before stage eight.

“As a social responsibility we’ve made the decision to withdraw,” said Mitchelton-Scott boss Brent Copeland.

Kruijswijk, ruled out of last month’s Tour de France because of a shoulder injury, said: “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.”

In a statement on their website, Team Sunweb said: “Michael is currently asymptomatic, feels healthy and is now in quarantine.”

A staff member from Team AG2R-La Mondiale and Team Ineos Grenadiers also tested positive and are now isolating.

The latest rounds of tests were carried out on 11 and 12 October.

Portugal’s Joao Almeida of the Deceuninck-Quick-Step team currently leads the general classification by 30 seconds after nine stages.

The Grand Tour race, originally scheduled for May, finishes on 25 October.

The Giro d’Italia appears to be unravelling before our very eyes, to what could be premature ending.

There are nearly two weeks remaining of this delayed Grand Tour, but the first rest day of coronavirus testing proves Covid 19 is now in the race ‘bubble’.

Following a relatively successful Tour de France, in which no riders were directly affected, Giro organisers RCS introduced the same model: pre-race testing and further tests on the two rest days.

They, and cycling’s governing body the UCI, must now consider at what point they would have to end the race early if more riders, or whole teams, pull out.

The loss of Kruijswijk blows the race further open, as he is the third of the favourites for victory to abandon after Simon Yates tested postive and Geraint Thomas of Ineos Grenadiers abandoned with an injury.

The ever colder Italian Alps await an unpredictable conclusion – if the race gets there at all.