Ruben Amorim said he has inherited a "difficult position" at Manchester United and described his new side as "a massive club but not a massive team."

Having racked up 20 top-flight titles, United are English football's most successful club, domestically. But their impressive history has not been mirrored by results on the pitch over the last decade.

Amorim has arrived at Old Trafford with United, who haven't won the title since 2013, in the bottom half of the table and they head into Saturday's game six points behind opponents Nottingham Forest -- who were playing in the Championship as recently as 2022.

"We're a massive club but we're not a massive team and we know it so it is no problem to say it," Amorim told a news conference on Friday.

"Our players have to understand that it's a very difficult position.

"We're not one of the best teams in the league and we have to say and think that clearly but our past, our club is maybe the best one in the league.

"So here we have a problem and we have to focus on the little things and little details."

Amorim has had little time on the training pitch since taking over from Erik ten Hag because of a packed fixture list.

The 39-year-old has been careful to play down expectations while the squad gets to grips with a new tactical set-up.

However, he insists one non-negotiable is the amount of effort put in by his players and warned them they had to "run like mad dogs" if they want to be successful.

"I think the way we sprint back, the way we sprint forward, the way we fight, we have to be very clear with the team, this is the first point we have to address then the tactical and technical aspects come later," Amorim said.

"What I see is that they're making an effort and there's a lot of room to improve. Changing that thing you can sometimes say is simple because it's just running but it's something in the head of the players.

"If you want to win we have to do it. Even with the best starting XI on the planet without running they will not win anything, that is very clear. If we want to win the Premier League we have to run like mad dogs. If not, we are not going to."