Bruno Fernandes said that Saturday's 2-0 loss to Manchester City in the Premier League showed Manchester United "are not at the same level" as their rivals.
An own goal from Eric Bailly sent the Citizens on their way at Old Trafford before Bernardo Silva doubled the away side's advantage in the closing stages of the first half.
Man City had 16 shots during a dominant performance against Ole Gunnar Solskjaer's side, and Fernandes admitted after the match that his team are an inferior outfit to the reigning champions.
"Difficult to say something now but not good enough from us. We have to change, this has happened many times already and we are at the beginning of the season," BBC journalist Shamoon Hafez quotes Fernandes as saying.
"We have to speak less and do more. We have to do better. They showed us today we are not at the same level."
Man United have now lost four of their 11 Premier League matches this season and could be 11 points off the top of the table entering the November international break.
