Erik ten Hag criticised his Manchester United players for not being ruthless enough on Wednesday night after conceding a last-gasp equaliser at Crystal Palace to miss the chance to go second.
Michael Olise's stunning 91st-minute free-kick cancelled out Bruno Fernandes' opener, and Casemiro's fifth booking of the season rules him out of Sunday's trip to leaders Arsenal.
Ten Hag rued the missed opportunity. 'We had control of the game,' he said. 'We needed to invest more for a second goal. If you score the game is over and now instead you get hammered with an unlucky moment in the end.
'I have to criticise my team. Go for the second. Bruno and Rashy (Marcus Rashford) on the wings, Alejandro Garnacho, a lot of creativity, speed and power, and Scott McTominay with penetration behind.'
Ten Hag was also frustrated by the decision not to give United a penalty in the 72nd minute at 1-0 up, when Scott McTominay went down in the Palace penalty box under pressure from defender Chris Richards.
Asked if United were unlucky not to be given a spot-kick, Ten Hag said: 'From my perspective (we should have had a penalty) but VAR and the referee make the decision. We have to accept it.'
Casemiro, involved in a bizarre second-half incident before his booking when a fan entered the pitch unchallenged by security for a selfie, came into the game one yellow card away from a suspension, but Ten Hag said he had no second thoughts about playing him.
He also insisted that United can go to leaders Arsenal and win, having beaten them at Old Trafford without the Brazil midfielder in September.
The Dutch manager said: 'This game was important, every game is important. Every game in the Premier League is a top game.
'His challenge was instinctive. He missed the ball. It's quite clear it would have been a dangerous situation. Casemiro wanted to stop it and that was his reaction.
'He is a really important player for us and one of the reasons we are in the position we are in.
'But we have a squad strong enough to fill that gap. The last time we beat Arsenal without Casemiro, so this time we need to do the same.'
However, goalkeeper David de Gea admitted that it was a loss for the club. 'It's a big blow to lose Casemiro for Sunday,' the Spaniard said. 'I don't get it why Arsenal don't play (this week) as we have to play and they don't.
'Now we are missing one of our best players. Now we miss him for a big game and it is a big loss for us.'
Palace manager Patrick Vieira, whose side had lost four of their five games since the World Cup, said: 'It was important not to lose the game. It was important to stay in the game and take a fully deserved point.
'When you go through a difficult period you have to keep working hard and we got rewarded. We showed some resilience and that will be really important for the rest of the season.'