Ruben Amorim has won just 18 of his 49 matches in charge at Manchester United, including nine out of 33 in the Premier League, where he has yet to win two successive games.
Sir Jim Ratcliffe reportedly remains supportive of the Portuguese coach, but failure to beat newly-promoted Sunderland on Saturday will put him under even more pressure.
"Nobody here is naive," he said. "We understand we need results to continue the project.
"We will reach a point that is impossible for everyone because this is a very big club with a lot of sponsors, with two owners.
"Of course, it's a dream to be here. I want to continue here and I want to fight for this, but the problem is now."
