Rafa Benitez says Jonjo Shelvey apologised to his team-mates for his sending off.
The Newcastle United midfielder was dismissed for stamping on Dele Alli in this afternoon's 2-0 Premier League defeat to Tottenham Hotspur.
Alli and Ben Davies netted against Benitez's 10-man team after Shelvey's sending off.
Asked if he felt let down, Benitez said: "“It’s not me, it’s everyone.
"We have talked about that for a while. He knows he has made a mistake and he apologised in the dressing room.
"But we lost the game."
Shelvey had started the game with the captain's armband.
Asked if Shelvey would skipper the team in future, Benitez said: "We will see."
On the game, Benitez added: "I was happy with the effort of the players.
"There were a lot of positives, but still if you want to win games then we can’t lose our focus for one minute.
"We know now we are in the Premier League, and we have to do everything really well if we want to win games.
“All the effort we put in on the pitch was lost because we did one mistake."
Benitez also felt Tottenham striker Harry Kane should have been dismissed for a challenge on Florian Lejeune.
"The tackle from Kane was worse (than Shelvey's stamp)," said Benitez.