Manchester United visit Goodison Park on Saturday after the international break and manager Louis Van Gaal on Friday confessed to suffering from sleepless nights after Arsenal's 3-0 demolition of his United side two weeks ago.
The Dutchman has called on his team to recover this weekend against Everton.
He said: "We cannot accept it because we want to be Champions.
"You have to improve. It has been an awful two weeks since that result.
"These are awful weeks because you are constantly thinking about how it happened and how you managed your players.
"But they fly out after that game and don't come back until Wednesday or Thursday after training.
"So they cannot participate in our meetings before the game at Everton.
"But you have to learn from it and improve and look at how you have prepared for that game with the players," the Dutch stated.
Meanwhile, Wayne Rooney, Michael Carrick, Ander Herrera and Marcos Rojo are all fit to face Everton this weekend, manager Van Gaal told MUTV on Friday.
Skipper Rooney and veteran midfielder Carrick both missed England’s recent Euro 2016 due to ankle and groin injuries, respectively.
But they are both available for Saturday’s trip to Goodison Park.
Van Gaal also revealed that Herrera and Rojo had been working on their recoveries during the international break and are fit for selection.
But he also said that it was unlikely that either player would be able to play for the full 90 minutes.
Rojo’s return from a hamstring injury is particularly important for United. With Daley Blind currently a starting centre-back and Luke Shaw out with a broken leg, Van Gaal has been short of left-sided defenders in recent weeks.
Right-back Matteo Darmian and winger Ashley Young are among the players to have filled in at left-back during Rojo’s layoff.