Luis Suarez is facing an abrupt end to his World Cup after FIFA announced it will investigate the striker for allegedly biting Italy's Giorgio Chiellini although the Uruguay man has sought to play down the incident.
Suarez is likely to face a lengthy ban that would keep him out of the rest of the World Cup - however far his country Uruguay progress - if he is found guilty.
The 27-year-old left teeth-marks on Chiellini's shoulder after clashing with him at the end of Uruguay's 1-0 win in Natal - where FIFA president Sepp Blatter was in attendance - that saw the South Americans qualify for the last 16.
A FIFA spokesperson told Press Association Sport: "We are awaiting the official match reports and will gather all the necessary elements in order to evaluate the matter."
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 attempted to defend himself following the incident, telling Uruguayan television: "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."
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.
Article 77 of FIFA's disciplinary code states the disciplinary committee is responsible for "sanctioning serious infringements which have escaped the match officials' attention" and "rectifying obvious errors in the referee's disciplinary decisions".
Suarez threw himself to the ground after the incident holding his mouth - Chiellini claimed that was a dive.
Chiellini told Italian television station Rai TV: "It was ridiculous not to send Suarez off. It is clear, clear-cut.
"Then there was the obvious dive afterwards because he knew very well that he did something that he shouldn't have done."
Italy boss Cesare Prandelli confirmed he had seen the bite-marks.
He said: "I didn't see Suarez biting him but I saw the bite-marks on his shoulder but the referee's assistants were so busy they didn't see anything.
"It's a shame, it's a real shame that it turned out like this."
Jim Boyce, Britain's FIFA vice-president and head of FIFA's referees committee, expressed concerns about Suarez's actions.
He said: "I have watched the incident several times on television. 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 deemed necessary."
After his two goals beat England on Tuesday, Suarez made reference to the criticism he had faced over his bans for biting Ivanovic and racially abusing Manchester United's Patrice Evra.
He said then: "Before the game too many people in England laughed about my attitude over the last few years.
"This is a very good time for me. I want to see what they think now."
However, Suarez refused to talk about the Chiellini incident and Uruguay closed ranks around their talismanic striker.
Uruguay skipper Diego Lugano said: "You couldn't have seen it today because nothing happened. The worst of everything is the attitude of Chiellini."
Uruguay manager Oscar Tabarez claimed Suarez was a target for sections of the media but said he had not seen a replay of the incident.
Tabarez said: "If it happened then I think the referee had to have seen it first. I didn't see the incident and I don't want anyone to speak for me about it.
"Suarez, in addition to errors that he may have made, is a target for certain sections of the media.
"If we believe people are attacking him, as has happened in this press conference, then we're going to defend him," he said. "He's a vital player, a very important person to the group."