The Premier League in England announced on Monday that 103 new coronavirus cases among club players and staff.
It was the highest weekly number recorded since testing figures began being circulated in May last year.
The league has also confirmed it has reverted to emergency measures following a raft of top-flight postponements.
Increased testing to daily lateral flow and twice-weekly PCR tests have been introduced.
Lateral flow testing was previously carried out twice a week.
“The League can today confirm that between Dec. 20 and Sunday, 15,186 COVID-19 tests were administered on players and club staff. Of these, there were 103 new positive cases,” read a statement.
“The Premier League’s COVID-19 emergency measures include protocols such as wearing face coverings while indoors, observing social distancing, limiting treatment time, as well as the increased testing.
“The League is continuing to work with clubs to keep people safe by helping mitigate the risks of COVID-19 within their squads.
“We are also liaising closely with the Government, local authorities and supporter groups, while being responsive to any future changes to national or local guidance.”