Police believe three men who attacked two teenagers after a football game were Middlesbrough FC fans.
The men assaulted the boys, aged 14 and 17, near the West Stand car park at the Riverside Stadium after the Stoke City vs Middlesbrough game on Saturday.
Cleveland Police said just before the attack, the boys had walked with a grandparent to see the Stoke City players after their team won 2-0.
Officers have urged anyone with information to contact the force.
Detectives said after one of the boys was hit, he fell backwards into a black Range Rover which was parked in the car park at about 17:00 BST.