UEFA said on Friday it was investigating incidents in Rangers' Europa League clash with Slavia Prague after the Scottish club's midfielder Glen Kamara complained of being racially abused by a visiting player in Thursday's 2-0 defeat in Glasgow.
Rangers were knocked out of the competition following a 3-1 aggregate loss in the last-16 second leg after finishing with nine men in a heated encounter which saw a melee on the pitch and clashes in the tunnel after the game.
"An Ethics and Disciplinary Inspector will conduct an investigation regarding the incidents that occurred," UEFA said in a statement.
Kamara was furious after Slavia centre back Ondrej Kudela leaned into his ear and said something while covering his mouth, sparking the melee in the final stages of the tie.
Rangers manager Steven Gerrard had called on European football's governing body to take action.
"My player tells me he was racially abused," Gerrard said. "I feel angry ... I know Glen and I trust him 100% and it is extremely disappointing.
"It is over to UEFA now this situation and I just hope it doesn't get brushed under the carpet."
Kudela said in a statement issued by Slavia that he had sworn at a Rangers player after being fouled, but denied using racist language. Slavia also alleged that Kudela was assaulted by Kamara after the game.
"Slavia resolutely denies the disgusting accusation... [against] Ondrej Kudela of racist behaviour," the Czech club said.
"Slavia players faced unprecedentedly malicious play from their opponents... After the end of the game, the team was not allowed to enter the dressing room.
"Ondrej Kudela was assaulted by Kamara and hit with fists in the head when Rangers manager Steven Gerrard witnessed the incident."
Slavia have since lodged an official complaint to the Scottish police, via the Czech Embassy in London, alleging a "physical assault" on Kudela.
"Physical assault on Ondrej Kudela was prepared and [a] deliberate act," the Slavia statement said. "The assault was brutal and carried out with the full force with the intention to hurt and cause physical harm to our player.
"In the text, the names of people who witnessed the incident are stated, including UEFA representatives and Rangers FC manager Mr. Steven Gerrard."
UEFA had said earlier on Friday it was aware of an incident in the tunnel involving players from both sides and was awaiting detailed information from the match officials.
Rangers' Kemar Roofe was also subjected to racial abuse on social media after being shown a red card for a high-boot challenge on Slavia's Ondrej Kolar, which the Czech club said resulted in the goalkeeper needing 10 stitches to his head.