Brentford boss Thomas Frank said his goalkeeping coach was injured after a pre-match altercation with a Nottingham Forest groundsman.
Frank claimed Manu Sotelo has marks on him after an argument with a member of the groundstaff before kick-off of the 2-2 draw and accused Forest of disrupting their pre-match warm-up.
The PA news agency understands Forest have conducted an early investigation and deemed Brentford to be at fault for breaching Premier League rules about how long teams can use the penalty area for during the warm-up.
The member of the groundstaff, who is understood to have felt threatened, went on to the pitch to move them on, but disrupted a drill.
The Football Association is aware of the incident and awaits Andre Marriner’s official report, with the referee intervening at the time.
Frank said: “It surprised me a little bit, not that I am an experienced, experienced Premier League manager, but in all my time in football and especially all my time in the Premier League I have never, ever, ever seen a groundsman walking around in the middle of our warm-up doing things.
“I don’t know if that is a coincidence, but it just surprised me very much. I have never seen that. I hope they do that every time, against Liverpool and West Ham.
“He got a mark. I don’t know what, something gave him a mark and I have even got a picture. I have a bit of a temper so I am not an angel all of the time and I try to be the best version but my goalkeeping coach is the most down-to-earth guy, there must be something really p***ing him off.
“I just hope everyone is looking into it. There must be cameras. I don’t know if you have seen it before or if it is a common thing.”
Forest boss Steve Cooper said he was aware of the incident but did not want to comment.
The incident was a precursor for a dramatic afternoon at the City Ground which included VAR drama and a Forest equaliser with the last kick of the game.
Forest deservedly went ahead through Morgan Gibbs-White’s first goal for the club before Brentford equalised on the stroke of half-time from the penalty spot through Bryan Mbuemo.
Marriner eventually ruled Dean Henderson to have fouled Yoane Wissa after checking it on the pitchside monitor, even though he did not give it live and the goalkeeper appeared to have played the ball.
Forest had a sense of injustice as they had three credible penalty shouts ignored by VAR.
Things got worse when Wissa scored with 14 minutes remaining to put Brentford 2-1 but there was one moment of drama left with Mathias Jorgensen’s own goal was awarded by goalline technology in the sixth minute of stoppage time.
Cooper, who was fined by the FA for previous post-match comments about a referee, believes if Marriner awarded one penalty in the game, he should have given four.
“My feeling on it is if the one he has given against us is a penalty then he has to give four in the game,” he said.
“The one on (Ryan) Yates, the one on (Emmanuel) Dennis and the one on Morgan. There is frustration there, if they have made him look at the screen on the one he has given why hasn’t he looked at the screen on the others.
“Just because he has looked at the screen doesn’t mean he has to give a penalty. If he has to go and look at that one, he has to go and look at the others. He has to. I am not saying they are penalties but if the one he has given is, the others are.
“The referee knew he touched it. If anything it is a decent save because he has got a decent touch on it and the referee knew he had. I’ve been to see him and we had a respectful conversation.
“That is that. I have said what I think on decisions. If there is one penalty to be given there has to be four.”
Frank said of the VAR drama: “It was a clear penalty.”