Chelsea head coach Enzo Maresca said Manchester United's Lisandro Martínez should have been sent off for going "for the legs" of Cole Palmer with a reckless challenge which resulted in a yellow card for the defender during Sunday's 1-1 Premier League draw at Old Trafford.
Argentina international Martinez was booked by referee Robert Jones in the third minute of stoppage time for the foul on Palmer in which he caught the England forward high on the knee.
Video Assistant Referee Michael Salisbury reviewed the challenge before announcing that Jones's on-field decision would stand because, according to the Premier League, it was deemed to be a "reckless challenge and not serious foul play."
Former United captain Roy Keane, working at the game as a pundit for Sky Sports, said, "Martinez is a lucky boy. It's a nasty tackle," and Chelsea coach Maresca claimed that he told the referee that Martinez should have been sent off.
"They [TV] showed me [the challenge] before the press conference," Maresca told reporters. "I think it's quite clear for all of us and they [officials] took a different decision.
"When there is no intention to go for ball and you only go for the player, it's a red. He [referee] didn't say nothing, but when you go for a player or the legs, there is no doubt about the decision. I think it is quite clear it is a red."
Ruud van Nistelrooy, United's interim coach, said he didn't see the challenge as a red, but admitted he had yet to see a replay of the incident.
"I haven't seen it," Van Nistelrooy said. "I saw it on the touchline and I didn't see it as a red, but I would have to watch it again to give an opinion."
Maresca, meanwhile, said that Chelsea are waiting to assess the full extent of Palmer's injury.
"He [Palmer] is waiting in changing room with ice," Maresca said. "We hope it's nothing important."