Police are investigating after Bilel Mohsni lashed out amid ugly scenes after the final whistle of the promotion play-off final as Rangers failed to return to the Scottish Premiership.
The former giants of Scottish football were bidding to return to the top-flight after a turbulent few years but lost 6-1 on aggregate to Motherwell.
Motherwell, who finished 11th in the 12-team top-flight, won the second leg 3-0 at home with second-half goals from Marvin Johnson, Lionel Ainsworth and John Sutton.
Emotions got out of control as the players left the pitch, with Rangers player Mohsni reacting to a push in the back from Motherwell's Lee Erwin. Tunisia international Mohsni turned around, kicked Erwin and also punched him.
Other players quickly became involved before Mohsni raced for the tunnel.
Police Scotland released a statement "in response to the disturbance at the end of the Motherwell v Rangers match".
Assistant Chief Constable Bernard Higgins said: "Police Scotland will conduct a full review of the circumstances and liaise with the appropriate partners, and decide how best to take the matter forward over the coming days."
Three red cards were dished out, to Mohsni and Erwin plus Motherwell defender Fraser Kerr.
Speaking to BT Sport after the game, Erwin said: "I tried to shake his (Mohsni's) hand to wish him all the best but he told me to 'f' off and reacted badly.
"I pushed him away and he reacted badly. A player at a club at that level should not be acting like that. It's embarrassing for him and the club."
Earlier in the match Rangers' Lee McCulloch had been involved in an altercation with Motherwell fans.
After the Mohsni incident Motherwell fans entered the pitch and could be seen taunting Rangers fans who were held in the stands at Fir Park.