Thousands of Mancheser City fans stormed the pitch after the team secured its fourth league title in five years.
The Swedish national team goalkeeper Robin Olsen made his league debut for Aston Villa but had a bad time after the 2-3 loss.
- My goalkeeper was attacked, said coach Pep Guardiola.
After the final signal, a person must have attacked Olsen in some way, it is unclear how.
The club apologizes on its website.
"The club has started an immediate investigation and once the individual has been identified, the person in charge will be suspended from the arena for life."
The text is updated.