Louis van Gaal has slammed Chris Smalling after the centre-back was sent of during the first half of the Manchester United's 1-0 defeat against Manchester City on Sunday, 2 November.
Smalling's second yellow card in the 38th minute helped City to secure a deserved 1-0 victory over van Gaal's side at the Etihad Stadium.
Having being booked for blocking a Joe Hart clearance when he had the ball in his hands, Smalling made a hard tackle on James Milner just five minutes later, leaving his side with 10 men with more than a half the game remaining.
"I didn't see the first yellow, but as a player if you know you have a yellow card you have to deal with that problem. I don't think he dealt with it very smartly. It was stupid," van Gaal admitted.
Minutes after Smalling's red card, Marouane Fellaini appeared to spit at Manchester City striker Sergio Aguero after the Argentinian asked for a penalty.
When questioned about that, van Gaal said: "I have heard that there is a question on social media.
"When you shout, sometimes a little bit of saliva is with it. I don't think he is a spitting figure."
Meanwhile, the United manager looked happy with the team's reaction to Smalling's red card.
"I said to the boys their willpower and labour were unbelievable and they can be very proud. The fans know the boys are willing to give everything for the shirt of the club. But at the end of the game, we have zero points. In this sport, it is always the goals that count.
"We were so close in spite of playing with 10 men. We had more chances [with 10 men] than in the first half. We are close but not close enough.
"We have 13 points out of 10 matches and Chelsea have a lot more, as do Manchester City, so we have a problem. We need to improve and prove that we are not close but better. We will improve, that I promise."
Marcos Rojo was forced to leave the pitch in the second half after dislocating his shoulder.
Speaking about that, van Gaal said: "His shoulder is out. We don't know how long that will take. I have to wait until Monday. But he shall not play against Crystal Palace, I don't think.
"We have very good players so I don't cry for the injuries. It's a pity, but it's not an excuse. When [Michael] Carrick and Paddy [McNair] came in we did fantastic. We can do it, but we have to score and today we didn't score that's why we don't have one point or three."