Yaya Toure did kick out Ricky van Wolfswinkel and the incident may have been worth a red card, Norwich boss Chris Hughton has claimed.
The Football Association is looking into the clash involving the Manchester City midfielder and if action is taken he would face a three-match ban.
The kick, during the 0-0 draw at Carrow Road, appeared to be missed by match officials and Hughton said: "It did go unnoticed and there was no doubt there was a slight kick out.
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"There was certainly something, but whether that was enough for a red card, then that is for the referee to decide on.
"It was a minimal incident in the game, and the bigger factor was it was a good team performance by us."
A suspension for the Ivory Coast international would be a hammer blow to City's title hopes after Manuel Pelligrini's side dropped two points at Norwich on the back of losing to current Premier League leaders Chelsea.
A three-match ban would see Toure, arguably City's most influential player this season, miss Wednesday's game against Sunderland, the FA Cup fifth round match against Chelsea at the weekend, and the league fixture against Stoke at a time when City are already stretched in midfield.
The only positive note for City is that all three of those games would be at home.
Pellegrini believes the title race will go to the wire.
He said: "This year the Premier League will be closer than ever. It is very difficult to know who are the favourites.
"The favourites were Arsenal because, after playing 25 games, Arsenal were leading the table for most of them.
"(Then) we were the favourites though, because we had been playing very well before this week.
"Chelsea are now playing well as well, but they are not the favourites - and don't forget about Liverpool, and maybe Everton or Tottenham.
"I think five teams are going to fight for the Premier League this season."