Sheffield United manager Neil Warnock accused Aston Villa striker Juan Pablo Angel of elbowing defender Chris Morgan in the closing stages of Monday's thrilling 2-2 draw between the two sides at Bramall Lane.
The Blades star pushed the Colombian striker who appeared to react by lashing out with his elbow and there were reports that the argument continued in the tunnel after the final whistle.
Villa boss Martin O'Neill confirmed: "There was a kerfuffle in the tunnel and a few words were exchanged.
"I was waiting there to speak to the referee and I'm not the tallest so I couldn't quite make it out.
"But there was nothing thrown or anything like that. There was just a lot of shouting and people separating them. I'm not too sure what happened."
However, Warnock insisted: "I saw Angel elbow Morgan in the box.
"But what a great game it was, although for a manager it was a bit of a nightmare. We just give teams massive lifts.
"We claw our way back into it and then we celebrate and give the ball away.
"A sloppy pass from Danny (Webber) on halfway and they end up scoring their second goal. I wish I'd taken him off when he'd scored."