Manchester United midfielder Fred was hit by an object thrown from the crowd during the Manchester derby.
The Brazilian prepared to take a corner when he was struck on the back of the head by an object, which appeared to be thrown from the home section.
The objects appeared to be a plastic bottle and a lighter in the incident in the 70th minute.
Fred held the back of his head and his shoulder as play was stopped by referee Anthony Taylor.
City midfielder Fernandinho was seen remonstrating with the supporters, urging them to behave as his side tried to get back into the game.
Referee Anthony Taylor eventually waved play to continue with United leading 2-0.
Marcus Rashford scored the opener from the penalty spot after being fouled by Bernardo Silva.
Anthony Martial added a quickfire second for the visitors.
City went into the clash 14 points adrift of Liverpool at the top of the table following their comfortable win over Bournemouth earlier in the day.
Fred was a target for Manchester City before he made a £53m move to Old Trafford in 2018.
He endured a difficult first season but has been in much better form since returning to the side this term, since the injury to Paul Pogba.
Pogba was in the stands at the Etihad but Ole Gunnar Solskjaer admits he is still a few weeks away from returning to the fold.
