Five men have been arrested as part of an investigation into violence at Middlesbrough FC's home ground earlier this year.
Cleveland Police described "pockets of disorder" at the Riverside Stadium and in the town centre on 12 February.
Fans attending the game against Derby County had been told to behave amid fears of tension over a resolved court dispute.
Seventeen others were arrested on the day of the Championship match.
Offences included assaulting emergency workers, failing to disperse and possessing a flare.
It followed legal proceedings launched by Middlesbrough, claiming Derby's financial breaches cost them a play-off place in 2018-19.