Marouane Fellaini's problematic first season as a Manchester United player has taken another turn for the worse after it emerged he is being investigated by the Football Association for a possible spitting offence against the Manchester City defender Pablo Zabaleta.

The FA is reviewing footage from City's 3-0 defeat at Old Trafford to establish whether Fellaini spat at Zabaleta in the aftermath of elbowing his opponent to the ground. Zabaleta was lying on the floor when the follow-up incident allegedly took place and the FA has seen footage, shot from behind Fellaini, that appears to incriminate the midfielder.

Zabaleta has also seen the television pictures and though City will not lodge an official complaint, the club are expecting the FA to look further into it. The Argentinian had his hands covering his face at the time and did not see, or feel, anything other than the blow to the side of his head from Fellaini's elbow.

If the FA thinks there is sufficient evidence, Fellaini will be charged with misconduct and the offence will carry a three-match ban, in line with George Boyd's punishment for his clash with Joe Hart when Manuel Pellegrini's team played at Hull City on 15 March.

The governing body will first request that Sky passes over its footage from various camera angles from the relevant passage of the game. United will also be asked to submit their own footage. As it stands, Fellaini's face cannot be seen and the FA is likely to need something more conclusive. Nothing was reported on the night and the referee, Michael Oliver, clearly did not see anything.

Fellaini was booked for the collision with Zabaleta but fortunate not to be shown a red card bearing in mind the seriousness of the offence. It is when he is protesting his innocence that he turns to Zabaleta and the TV cameras capture the footage that is now in the possession of the FA's disciplinary investigators.

Fellaini has not scored once in his first season at United and his performances were criticised by Paul Scholes during his TV analysis of the defeat to City. The Belgian's substitution was cheered by the home crowd, just as it was in the 3-0 defeat against Liverpool, and his explanation for the elbow has not been entirely convincing. "I certainly didn't do it on purpose," he said. "I put my arm up to try and protect possession of the ball, and Zabaleta bounced against it. He was unlucky to make contact."