Peter Sagan soloed to victory in the Giro d'Italia's 10th stage after two teams, Mitchelton and Jumbo-Visma, were forced to pull out before the stage because of positive Covid-19 tests.
Sagan, who lost out to Sam Bennett in the Tour de France Green Jersey race, ended his winless drought going back to the 2019 Tour de France. Portugal's Joao Almeida kept the leader's pink jersey.
"I won with my style, putting on a show!" said 30-year-old Sagan.
"We were in the breakaway all day, I had good legs, and went solo on the uphill before descending with care in the downhill and then full gas in the final kilometres."
Mitchelton pulled out before the start of the 177km stage because of four positive tests, and Jumbo followed after Dutch contender Steven Kruijswijk tested positive.
Kruijswijk, who finished third in the 2019 Tour de France, returned a positive test along with Sunweb's Australian Michael Matthews.
"We are trying to keep the situation under control," said Giro race director Mauro Vegni.
"This morning, all the teams that have had positive cases have undergone new quick tests and we will do the same the day after tomorrow. So far we have done almost 1,500 tests and it is impossible to do more."
Sagan, one of the most successful riders in the peloton with three world titles, achieved his first success in the Giro, to complete his set of stage wins on the three big tours - France, Italy, Spain.
The Slovak attacked several times in the mountainous last 60km, finally breaking clear uphill 12km from the finish line to cross alone 19sec ahead of American Brandon McNulty with Almeida third at 23sec.
Danish Jakob Fuglsang was the day's biggest loser after suffering a puncture 10km from the finish and losing a minute on his rivals.
The peloton was reduced to 145 riders from the 176 who started the race in Sicily on 3 October.
The Mitchelton team said they had been notified of four positive results for "staff members" after tests conducted on Sunday.
"Upon receiving the results, Mitchelton-Scott immediately withdrew its team from the race and will focus on the health of its riders and staff and their safe movement to areas of quarantine," the team said.