British and Irish Lions fullback Stuart Hogg on Sunday denied that he bit South Africa counterpart Willie le Roux during the second Test in Cape Town.
The accusation followed inconclusive footage of an altercation between the backs during the match, which the Springboks won 27-9 to level the series ahead of the August 7 third Test decider.
"Following speculation that has surfaced online, I would like to categorically deny any foul play in the game," Scot Hogg said in a statement.
"I would never bite an opponent and I am annoyed and upset by this unsubstantiated accusation. I have always been proud of playing rugby in the spirit of the game.
"Respect to the Springboks for their deserved win yesterday.
"The squad is hurting after the defeat, but it is all to play for next week. It is going to be a cup final and everyone is going to be up for it."
The citing window for disciplinary action has been extended to 24 hours, meaning the authorities have until late on Sunday to announce any charges.
Others who could face action include Lions lock Maro Itoje and Springboks winger Cheslin Kolbe and scrumhalf Faf de Klerk.
A video clip shows Itoje kneeling on the chest and neck area of South Africa centre Damian de Allende.
Kolbe could be cited after escaping a red card for taking out Conor Murray in the air, as could De Klerk for a no-arms high tackle on the Lions' scrumhalf.