Fines have been issued after about 200 fans gathered in a town with England's second-highest Covid rate after Rangers won the Scottish Premiership.
Northamptonshire Police was called to Abington Fields in Corby, which is known as "Little Scotland" due to its high proportion of Scots, on Sunday.
Video shared on social media and messaging apps showed people singing Rangers' songs.
Police issued three fines and said the organiser would be fined £10,000.
The Corby district recorded 119 cases in the seven days to 2 March.
According to latest figures, this gives the area a rate of 164.8 cases per 100,000 of the population.
Although this is 45% less than the previous seven days, only Leicester has a higher infection rate with 166 cases per 100,000 people.
Corby gained its nickname after many Scots migrated south to work in the town's steelworks in the 1930s.
Northamptonshire Police responded to reports of a "large number of football supporters" gathering in Corby and said the behaviour was "ridiculous".
"The time for engaging, explaining and educating people in regards to the rules has passed - everyone knows what they should and shouldn't be doing," a force spokeswoman said.
"So many sacrifices have been made in the past year and we can see the finish line. It's blatant disregard like this that could set us back."
Supt Elliott Foskett said it was "irresponsible behaviour".
"A lot of people dispersed as soon as the officers turned up which indicates people knew straight away that they were breaking the law," he said.
The force said it was reviewing video footage in order to "retrospectively fine" those that made off, and it had also identified the organiser.
Supt Foskett said it issued 177 lockdown fines over the weekend across Northamptonshire, including 19 fixed penalty notices at an incident in Towcester and four at a house party in Raunds, where more than 50 people were present.
"It's just unthinkable that people don't recognise that this is still a risk and that they don't understand what the law is," he said.
"If we disregard the law now... it's going to make it worse."