Rafael Da Silva has been charged with improper conduct by the Football Association for his reaction to referee Mike Dean after being dismissed against Tottenham.
But team-mate Patrice Evra backed the defender, praising his display in Sunday's 0-0 draw at White Hart Lane.
"Rafael did a great job," said Evra. "He is a strong defender. You need that against a player like [Gareth] Bale." United goalkeeper Edwin van der Sar was similarly complimentary: "It was a high pressure game for him. He played really well. He's only 20 and he's doing a great job. He'll have plenty more years at this club."