Brisbane Roar confirmed they reported the incident on behalf of their fans and players to the FFA, which has not ruled out forwarding the case to the disciplinary committee. The Roar were furious with the conduct of their former long-serving player. In a post-match interview, Roar defender Corey Brown told reporters that he asked Nichols to stop his tirade while on the field.

"FFA is considering reports on the incident involving Mitch Nicholls immediately after the semi-final," an FFA spokesperson said. "The matter remains under investigation."

It is understood Nichols will be forced to explain himself to the FFA this week and may still face potential sanctions, including a possible suspension, if found guilty for inciting rival fans and breaching the national code of conduct.

Two fingered salute: Mitch Nichols has been fined for his post-match celebrations after the Wanderers last gasp victory over the Brisbane Roar in the A-League semi finals. Credit:Getty Images

"The club is very disappointed to see the image of a former championship player and the actions he took towards our supporters. We believe the investigation is being conducted by the FFA into the matter and we will await the outcome of that investigation," Roar chief executive David Pourre said. "From a professional athlete and player across the A-League and knowing that it has a far-reaching broadcast, it's very disappointing to see that type of behaviour and it's unacceptable."

Brisbane Roar players were incensed with Nichols' action, in particular that he ran more than 50 metres out of his way over towards their supporters to insult them, having not been on the field at the sound of the final whistle.

Nichols was substituted at the end of 90 minutes and played no part in the extra-time drama. A photo shows the midfielder raising his fingers at Brisbane fans shortly after leaping from the substitutes bench after full-time and continuing to do so until in close proximity of the away bay.

Nichols was wearing an orange substitutes bib and had already removed his playing jersey.

"There's an issue there and he needs to address it because it's not what we want to see in the competition, people acting in that behaviour, it's unacceptable," Pourre said.