Man Utd played Brentford in a friendly on Wednesday
Manchester United are back in training after the first team were given the all-clear from further Covid-19 testing.
United's pre-season friendly at Preston on Saturday was called off after a "small number of positive" cases were identified at the Premier League club.
United drew 2-2 against Brentford on Wednesday and routine lateral flow testing of first-team players and staff the following day showed some positive cases.
However, further PCR tests on Friday were all negative.
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United said in a statement: "Following consultation with the Premier League they are satisfied that all Covid protocols have been followed correctly and the squad can return to training immediately."
Ole Gunnar Solskjaer's side's only remaining friendly scheduled before the start of the season is against Everton on 7 August, a week before they begin their Premier League campaign against rivals Leeds.
United say any supporters who purchased tickets for the Preston game will be given a full refund.
On Thursday, Nottingham Forest were forced to cancel Saturday's pre-season game against Burnley at the City Ground because of Covid-19 cases at the club.
On the same day, Norwich City's pre-season game against Sheffield United was also cancelled because of a "small number" of cases in the Canaries' squad.
Earlier this month, Arsenal withdrew from the Florida Cup after a "small number" of their touring party tested positive for coronavirus.
Newcastle will have no senior goalkeeper for Sunday's friendly against York after Karl Darlow tested positive for Covid-19 and must isolate for 10 days.
Due to being in close contact with Darlow, Mark Gillespie and Freddie Woodman must also do the same, while Martin Dubravka is injured.
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