Marcus Rashford criticised Manchester United's work-rate and mentality after a derby defeat at home to Manchester City left Pep Guardiola's side with one hand on the Premier League trophy.
Bernardo Silva opened the scoring at Old Trafford on Wednesday and victory for the visitors was secured when a Leroy Sane drive went straight through United's out-of-form goalkeeper David de Gea.
United, who have lost seven of their past nine games in all competitions, had little response with Rashford fronting up in a strong response to another sub-par display that followed Sunday's thrashing at Everton.
"It was quite clear who the better team was," Rashford said to Sky Sports.
"We didn't play like Man United and the last few weeks it hasn't felt like Man United. It's not right. The bare minimum should be to work hard and give your all for the supporters and the badge.
"It's been a tough road to get to where we are, we weren't expected to get to this position. But to not be putting in the performances from the beginning of January is disappointing.
"We need the mentality and willingness of running for your team."
United now have lost their last three Premier League derby matches at home to City, with Rashford refusing to make excuses.
"Forget the league and top four, you don't lose this game. It's that simple as a Manchester United fan," Rashford added.
"We never call each other out but we have to be real with each other. It's a matter of trying to improve each other.
"It's more getting back used to doing it on the pitch. They [the supporters] know we can do it.
"Forget the top four and the Champions League. We have to get to the bottom of it and start playing like Manchester United, for ourselves."