Luis Suarez could face a lengthy ban that would force him to miss the rest of the World Cup if found guilty of biting Italy's Giorgio Chiellini.
Fifa, football's governing body, opened disciplinary proceedings after Uruguay's 1-0 win on Tuesday and has requested television footage.
Chiellini claimed Suarez bit him on the left shoulder, but Suarez said the defender "bumped" into him.
Suarez, 27, could be banned for up to 24 matches or two years.
Fifa said in a statement: "The player has the right to be heard and has until 21:00 BST to submit all documentation.
"The disciplinary committee does not yet have all the elements to discuss the matter. We cannot speak about what could potentially happen. This is in the hands of the disciplinary committee.
"The body pronouncing the sanction decides the scope and duration of it - so we really cannot anticipate what could or could not happen and that's all we can actually say.
"The disciplinary committee understands the urgency of the matter because Uruguay are still in the competition."
Mexican referee Marco Rodriguez took no action following the incident, but Fifa can still punish Suarez.
Radio 5 live's Richard Conway, who is in Brazil to report on the World Cup, said: "Given that spitting at an opponent carries a minimum tariff of six games, you would expect biting to carry a ban in excess of that.
"That gives you the benchmark many people are working on and would mean his World Cup would be over."
Former Liverpool midfielder Jan Molby expects Suarez to be banned for the rest of tournament.
The Dane told the Liverpool Echo newspaper: "I'm sure Fifa will make an example out of him. Obviously, his World Cup is over and I would expect Fifa to give him a long international ban."
The longest ban in World Cup history is eight games, handed out in 1994 to Italy defender Mauro Tassotti for breaking Spain's Luis Enrique's nose with his elbow during the second half of their quarter-final.
Uruguay face Colombia in the last 16 on Saturday after finishing second in Group D behind Costa Rica.
Suarez's actions have already received widespread condemnation.
Former England captain Alan Shearer told BBC Sport: "The pictures are damning and I don't see how he can get away with it."
Chris Waddle, a member of England's World Cup squads in 1986 and 1990, said: "There will be people who will defend him, but I don't know why. I'd make him wear a gumshield."
Suarez has twice been suspended for biting opponents.
The Liverpool forward was given a 10-game ban for biting Chelsea's Branislav Ivanovic's arm during a Premier League match in April 2013.
He was also suspended for seven games for biting PSV Eindhoven's Otman Bakkal's shoulder while Ajax captain in 2010.
In December 2011, Suarez was also given an eight-match suspension and fined £40,000 for racially abusing Manchester United's Patrice Evra.
After the Ivanovic incident, Liverpool said they had spoken to Suarez about his "unacceptable" behaviour.
"This is a club with incredible values and ethics," said Reds boss Brendan Rodgers at the time. "There's certainly no-one bigger than this club, a player or manager."
Suarez has also been criticised during his career for diving and stamping during games, prompting former Liverpool director of football Damien Comolli to suggest the Uruguayan could be driven out of England.
"This is a person who definitely needs some help," former England boss Graham Taylor told Radio 5 live.
"If you look at Suarez's reaction afterwards, it's like he knows what he's done."
Last season, he helped Liverpool to a second-placed finish in the Premier League, winning the Golden Boot with 31 goals in 33 games.
He was named player of the year by both the Football Writers' Association and Professional Footballers' Association.
Liverpool have not made any comment on the latest incident and will let Fifa deal with it before deciding on any action.
Asked about the alleged bite, Suarez told Uruguayan television after the game: "There are things that happen on the pitch and you should not make such a big deal out of them. It was just the two of us inside the area and he bumped into me with his shoulder."
Chiellini, 29, described Suarez as "a sneak".
He added: "I'd love to see if Fifa has the courage to use video evidence against him. The referee saw the bite mark but he did nothing about it."
Fifa vice-president Jim Boyce said: "There is no doubt Luis Suarez is a fantastic footballer but, once again, his actions have left him open to severe criticism.
"Fifa must investigate the incident seriously and take whatever disciplinary action is deemed necessary."
After the clash between the players, Suarez fell to the ground holding his mouth, apparently suggesting he had been elbowed.
Chiellini ran after the referee to show him the alleged bite mark, pulling his shirt down to bare his left shoulder.
As he did so, Uruguay forward Gaston Ramirez tried to stop him by pulling the Italian's jersey back into place.
The incident occurred towards the end of the game, shortly before Suarez's team-mate Diego Godin scored the only goal of the match.
Godin's header eliminated four-time champions Italy from the 2014 Fifa World Cup and secured Uruguay, semi-finalists in South Africa four years ago, a match against Colombia in the next round.
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