Steven Gerrard claims Aston Villa keeper Robin Olsen was assaulted by Manchester City fans who invaded the pitch on Sunday.
Pep Guardiola's team came from two goals down to clinch their fourth Premier League title in five years and celebrations spilled over at the Etihad.
Thousands stormed onto the pitch as they pipped Liverpool to the post and Villa boss Gerrard says at least one of his players was "attacked."
When asked if his players made it off the pitch OK, he said: "No is the answer to that.
"My goalkeeper was attacked and I think those questions should go to Pep and Manchester City.
"We'll go and check if he's OK now."
Manchester City have now issued a statement in response which reads: "Manchester City would like to sincerely apologise to Aston Villa goalkeeper Robin Olsen, who was assaulted after the final whistle at today’s match when fans entered the pitch.
"The club has launched an immediate investigation and once identified, the individual responsible will be issued with an indefinite stadium ban."
Villa had led 2-0 and appeared to be on the brink of handing the title to Liverpool only for an Ilkay Gundogan double and a Rodri strike to snatch it away.
The former Rangers boss finished the season in 14th place with Villa.