Manchester United must act like champions and bounce back from the "unacceptable" 3-0 loss to Arsenal in a positive fashion, says manager Louis van Gaal.
United sit two points adrift of Premier League leaders and rivals Manchester City following defeat at the Emirates Stadium before the international break.
Dutchman Van Gaal has now called on his team to show the character of title contenders and respond with a win against Everton on Saturday.
"We cannot accept it – not only my members of staff, but also the players," Van Gaal said.
"We can't accept it from each other because we want to be champions, so we must behave like champions. You have to improve every time.
"I have to see how they recover from that defeat to Arsenal. It cannot happen again.
"I am confident. I have seen the training sessions and the reaction of my players."
After their visit to Goodison Park, United travel to CSKA Moscow in the Champions League before hosting City on October 25 and the Van Gaal knows it will be a tough spell for his team.
"It's a big challenge because we have to compete in different competitions," he added.
"Everton has always been difficult for United in history, then Moscow, the Champions League at the highest level.
"Then we have to play against our competitor, City. It is a very heavy week so we have to be prepared for that. After an international break it is not easy.”
Striker Anthony Martial was named Premier League player of the month for September after scoring three goals in three appearances.
However, Van Gaal tempered expectations on the 19-year-old by acknowledging it will be difficult to produce such displays on a regular basis.
"I'm very pleased he's started so well. It's also good because most of the fans didn't know him – now they know him and also a little bit about his qualities and talent," he added.
"Still, we have to be patient with him. He is still 19-years-old and he cannot do that every match. That is also a characteristic of a young player."
Wayne Rooney will be available for the match against his former club, while Ashley Young (calf) has been ruled out.
