FIFA has opened disciplinary proceedings against Uruguay striker Luis Suarez after he appeared to bite Italy defender Giorgio Chiellini during their World Cup match in Natal on Tuesday.
The incident occurred in the latter stages of the Group D encounter, which Uruguay won 1-0 to progress to the knock-out stages, and although the incident was missed by the match referee FIFA's disciplinary committee has taken retrospective action and Suarez could be facing a lengthy ban that would keep him out of the last-16 match against Colombia and beyond should Uruguay progress.
Uruguay and Suarez have until 5pm local time (9pm BST) on Wednesday to provide evidence.
A statement on FIFA's website said: "FIFA can confirm that disciplinary proceedings have been opened against the player Luis Suarez of Uruguay following an apparent breach of art. 48 and/or art. 57 of the FIFA Disciplinary Code during the 2014 FIFA World Cup Brazil match Italy-Uruguay played on 24 June 2014.
"The player and/or the Uruguayan FA are invited to provide with their position and any documentary evidence they deem relevant until 25 June 2014, 5pm, Brasilia time.
"According to art. 77 lit. a of the FIFA Disciplinary Code (FDC), the FIFA Disciplinary Committee is responsible for sanctioning serious infringements which have escaped the match officials' attention.
"Furthermore, according to art. 96 of the FDC, any type of proof may be produced (par. 1), in particular are admissible, reports from referees, declarations from the parties and witnesses, material evidence, audio or video recordings (par. 3)."
FIFA's disciplinary code sets a maximum ban of 24 matches or two years, but the longest ban in World Cup history was eight games for Italy's Mauro Tassotti for breaking Spain's Luis Enrique's nose in 1994 with an elbow. Zinedine Zidane was given a three-match ban for headbutting Marco Materazzi in the 2006 final.
Suarez has twice been banned for biting opponents - for 10 matches in 2013 for biting Chelsea's Branislav Ivanovic, and in 2010 he was given a seven-game ban while playing for Ajax for biting PSV Eindhoven's Otman Bakkal.
FIFA's disciplinary code allows action to be taken retrospectively via video evidence even if the incident has been seen by the referee.
Suarez moved to defend himself on Uruguay television after the flashpoint.
He said: "These situations happen on the pitch, we were both just inside the area, he struck me in the chest with his shoulder and he hit me in the eye as well.
"These are things that happen on the pitch and you shouldn't attach so much importance to them.
"I'm very happy to have qualified. We are taking each game as it comes, we know that we're in a difficult situation, we're at our limits now."