Sergio Aguero could be facing a potential ban for the Manchester derby after an apparent elbow on Winston Reid during his side's 3-1 victory over West Ham.
Manchester City striker Aguero and Reid were involved in a flashpoint during Sunday's clash at Etihad Stadium, when the pair tangled while challenging for a long ball in the 76th minute.
Referee Andre Marriner appeared not to see the incident but after Reid hit the deck, television replays showed Aguero flailing an arm that made contact with the New Zealander's throat.
The West Ham defender was subsequently forced off with his injury, and the Football Association could now review video footage of the incident to decide whether any retrospective action should be taken.
Should a ban be imposed, Aguero could miss the derby date against arch-rivals United, which is next up for City on September 10, after the international break.
City manager Pep Guardiola insisted he did not see the incident, although he was philosophical about the prospect of his forward being sanctioned.
"Hopefully nothing happens," he said. "If it happens, we accept and adapt.
"If we lose him, we lose him. We are going to play with 11."
West Ham boss Slaven Bilic, meanwhile, also missed the clash in real time, but the loss of Reid to injury was another blow to his already under-strength squad.
The Croat said he was "angry" at his side's first-half display, which saw them two down inside 19 minutes to goals from Raheem Sterling and Fernandinho.
That deficit could have been greater, and to their credit the visitors were much improved after the break - with Michail Antonio heading home after 58 minutes to give them a way back into the game.
But when Sterling added his second injury time to cap a fine individual display, it was no more than City deserved.
And Bilic was left rueing the absence of the likes of Manuel Lanzini and Dimitri Payet - both still recovering following their close-season exertions at international level - as well as Sofiane Feghouli (hamstring) and Andy Carroll (knee).
"Man City were much better in the first half. They started better, were quicker, more aggressive and were better on the second balls," said Bilic.
"We gave them far too much time and space on the ball and they scored two goals.
"To be fair, at half-time I was angry about our mentality and character. We showed our quality and you need to show keeping the ball and wanting to hurt them.
"We played well in the second half but the team showed character, spirit and something up front. We have an awful lot of players missing.
"I expect a few players back after the [international] break - Lanzini, Payet, Feghouli and hopefully Carroll won't be long too."