The commanding and well-deserved victory saw United into the fourth round, with many squad players impressing at Old Trafford. Alejandro Garnacho gave them the lead, before Casemiro and Anthony Martial added gloss to the scoreline.
Moroccan midfielder Amrabat was handed his first start for the club since joining from Fiorentina this summer, and produced an excellent display — starting at left-back, before moving into central midfield after half-time.
“Sofyan is a player who, where the team needs him he will play,” said Ten Hag. “It’s one of the reasons we signed him. Every player has his best position, but he gives a certain dynamic in the game.
“We just started, and the process was a little bit interrupted by the many injuries we had. You see with Mason [Mount], Amrabat — they can contribute to the game and they will do.”
Newly signed goalkeeper Andre Onana has come in for stick in recent weeks after a number of high-profile errors in the Premier League and Champions League, but Ten Hag praised the Cameroon international after he kept a clean sheet on Tuesday night.
“Of course, a clean-sheet will always give a keeper confidence, especially when you contribute,” the United boss said.
“He had two fantastic saves. That will help in building his confidence. He has personality.
“It was a good night, definitely. We dominated the game. We had some good attacks, controlled possession, created chances, and scored great goals.”
Addressing United’s poor league form in which United have won three and lost three of their six fixtures so far, the Dutchman added: “When you are not winning at United, there is frustration, there is disappointment.
“We know we are not in the position we want to be, so we have to catch up. The next game is the most important — always.”
United host Palace once more on Saturday, as the two sides meet in the Premier League.