Eric Dier's altercation with a supporter following Tottenham Hotspur's FA Cup defeat to Norwich City is being investigated by the Football Association (FA).
The PA news agency understands the England midfielder's confrontation with an individual in the West Stand at the Tottenham Hotspur Stadium is being looked at.
The 26-year-old is likely to face disciplinary action from the FA over the incident.
Dier went into the crowd to confront a supporter who was arguing with the player's brother.
Tottenham manager Jose Mourinho said he understood why he did it and hoped the club would not take disciplinary action against Dier.
It is understood Spurs will conduct a thorough review of the incident.
Mourinho said: "I think Eric Dier did something that we professionals cannot do but, in these circumstances, every one of us would do.
"Because when somebody insults you, and your family is there, and you get involved with the person that is insulting you, in this case, a younger brother, I think Eric did what we professionals cannot do."
The incident happened in the area behind the dugouts, which is a corporate section, and Mourinho has criticised it for not housing "real Tottenham fans".
"Of course, some are Tottenham fans, but I think a lot of corporate," he said.
"A lot (are thereby) invitation, a lot of people with special status and probably it's the place of the stadium where I sometimes have doubts over if they are the real Tottenham fans because these (real fans) are the ones who support the boys until the last."
- TEAMtalk media