Erik ten Hag said it was difficult to integrate new players into his squad effectively so early in the season after his team lost 3-0 to Liverpool at Old Trafford on Sunday, adding: “I’m not Harry Potter.”

In a fierce defence of his record during a sometimes tense post-match press conference, the Dutchman assured fans his team would perform “fine” and have a “great chance” of winning another trophy at the end of the season.

“It’s only the third game of the season, we have to put together a new team,” said Ten Hag.

“I’ve explained this so many times. We’re going to build it up. We have young players and players to build on. Today we had three players who started for the first time this season. It will be fine. It’s clear that we have to improve, but at the end of the season I’m confident that we have a great chance to win another trophy.”

Ten Hag had to replace Casemiro at half-time after the Brazilian made two mistakes, which led to goals from Luis Díaz.

New signing Manuel Ugarte, valued at £50 million ($65.6 million), watched from the stands after being brought onto the field before kick-off, with Ten Hag admitting the Uruguayan needs time to get up to speed.

“Here’s another one. We have to get him into the team,” he said.

“It will take time, so I am not Harry Potter. That is what you have to recognize. And if you see Manuel Ugarte, he has not played in the season. Not a single minute of play. He has to build up his fitness and then we have to build him up in the team.”

Ten Hag subsequently rejected suggestions that his team would continue to be punished for known mistakes.

“Perhaps you can explain to me what those errors are,” he replied.

“Are you sure? I don’t think so, otherwise you wouldn’t be winning trophies like we have. I feel sorry for you. I think we have won the most trophies in English football in the last two years after (Manchester) City, so I feel sorry for you.

“There are (positive) things, but I don’t want to talk about it. It hurts, it hurts, especially for our fans, we have to be humble and move on.”