Leeds goalkeeper Casper Ankergren was subjected to taunts by the Millwall fans following the goal and also had missiles thrown at him, and Scotland Yard have confirmed that one man has been arrested on suspicion of assault.
Related ArticlesHarris gives Millwall the edgeLeeds and Millwall unitePredict scores and resultsUefa asked to probe Leeds defeatChelsea striker Didier Drogba cautioned for throwing coin at fansG20 protests: Troublemakers will be tracked down, warn policeThe FA's decision to look into the incident comes on the back of the Danish goalkeeper's plea for action be taken against the London club.
"There was something thrown at me, I didn't see what it was as I turned my back on it," he said.
"It's very bad for football and Millwall should be punished.
"I was pushed in the back by one of the fans that came on the pitch too. It should never happen, fans should not be allowed on to the pitch.
"I'm not sure what the security were doing as no-one came to remove them. They are meant to be here to protect the players, it's not good enough.
"Anything could have happened, luckily it didn't and hopefully I wouldn't experience that again.
"English fans are normally much better than Danish fans, who always throw stuff on the pitch and at players.
"But it's happened here at Millwall and I hope something will be done. It is a disgrace to football."
Millwall have confirmed that any fans arrested will be banned from all their games for the foreseeable future and that Ankergren has received apologies from the club.