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Three Premier League matches in a week have now been called off because of outbreaks of Covid-19.
Three of the weekend's Championship games have already been called off.
And in rugby, Saracens' European Challenge Cup game with Pau on Saturday has also been postponed.
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How have new Covid cases affected men's football?
New Covid rules in England were announced last week to help limit the spread of the Omicron variant.
As a result, the Premier League told clubs to return to emergency measures, including social distancing and wearing masks.
Tottenham's Europa Conference League match against Rennes last Thursday was called off after 13 positive tests at the north London club, followed by their Premier League game at Brighton, scheduled for Sunday.
On Monday, the Premier League confirmed that 42 players and staff had tested positive for Covid-19 over the previous seven days - the most recorded in the league over a seven-day period.
Brighton, Tottenham, Leicester, Manchester United, Aston Villa and Norwich have all confirmed cases, and United's game at Brentford on Tuesday was postponed.
Leicester's game with Tottenham is due to go ahead on Thursday, despite both clubs asking for it to be postponed, with the Foxes without nine players because of Covid-related issues and injuries.
But less than three hours before kick-off on Wednesday, Burnley's game was called off because of an ongoing Covid outbreak at their opponents Watford.
And in the Championship, an outbreak at QPR has resulted in the postponement of Monday's trip to Sheffield United and Saturday's home game with Swansea City.
Cases at Reading and Millwall mean two more of Saturday's Championship matches are off.
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How about other sports/leagues?
Wednesday's Women's Continental League Cup between Leicester and Manchester City was called off "following a number of further positive Covid-19 cases" among the visitors' squad.
Keira Walsh and Janine Beckie both missed Man City's Women's Super League match on Sunday after testing positive, and Lucy Bronze withdrew "under test and trace guidelines".
Three Leinster rugby players and a member of staff tested positive for coronavirus before Saturday's Champions Cup win over Bath and the Irish province have said "an additional number of senior players" have tested positive before Friday's game away to Montpellier.
"Several positive cases" emerged after a round of PCR testing at Saracens on Monday, meaning Saturday's European Challenge Cup game with Pau has been called off.
The English side have shut their training ground with all players, coaches and support staff having gone into isolation.
It is the second game in European rugby to be called off this season with Scarlets' Champions Cup clash with Bristol cancelled due to quarantine issues after the Welsh club's return from South Africa, where the Omicron variant was first reported on 24 November.
In tennis, Britain's Emma Raducanu is isolating after testing positive for Covid-19, which forced the US Open champion to withdraw from the Mubadala World Tennis Championships in Abu Dhabi.
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