Ruben Amorim has swiftly asserted his authority on the Manchester United dressing room since being appointed head coach, with the Portuguese reportedly having three ‘bans’ in place.

A month into his Old Trafford tenure, the charismatic Amorim has endured a mixed bag of results - three wins, two losses and one draw in league and European matches. But the 39-year-old holds steadfast in his mission to bring change at United through several strict measures - or ‘non-negotiables’ - ahead of a hectic winter schedule.

His first major rule at Carrington was to ban coaches from giving complex instructions, insisting that if an idea cannot be explained in a single sentence, it should not be communicated until it has been simplified. This is particularly crucial as he has had to change the team's formation to a 3-4-3, which is new to the majority of the team.

His players have responded positively to this approach, having been struck by the "clarity" with which Amorim speaks, as well as his dedication to ensuring they fully grasp his instructions down to the smallest detail.

He has also addressed another long-standing issue with a firm hand. There was plenty of noise surrounding Marcus Rashford and Casemiro’s decisions to fly to the United States during November's international break, when they had only been given a few days to rest.

Rashford jetted off to an NBA game in New York while Casemiro, who enjoyed a family holiday at Disney World, Florida, also watched an Orlando Magic game. Red Devils legend Gary Neville didn't hold back his criticism and asked the new United head coach his thoughts regarding the situation. Amorim, who was left to work with a skeleton squad last month due to the majority of his players being on international duty, defended the duo but said he would clamp down on such trips in the future.

Speaking about his ban on using international breaks as holiday opportunities, he said: “Would I set a different structure? Yes, for sure. But we cannot put this on the players. They told them they have five days off so they can fly anywhere. Because nobody in the club says you cannot fly. So we cannot, this time, put that on Rash or Case.”

Amorim said about the changes he will implement: “We as a club have to set the standards and manage that. It’s my decision if they can have five days, or three days, or three days to rest and you cannot fly. This is something that us as a club have to decide. So this must be started in the club, with us and me being responsible in that area.”

With the Red Devils languishing in 13th in the league ahead of Amorim’s first Manchester Derby on Sunday, ESPN reports that Amorim has laid down another strict rule: banning food in the dressing room on matchdays.

It comes after he recently emphasised the need to improve his squad's physical fitness. Speaking ahead of their defeat to Forest last weekend, Amorim said it was "impossible" to win the Premier League without a team that doesn’t run. "You can do a starting line-up with the best players on the planet, without running they also won’t win," he said. "We have to run like mad dogs, if not we won’t win.”

Having clinched a 2-1 comeback victory against Viktoria Plzen on Thursday night thanks to a brace from Rasmus Hojlund, Amorim's squad will head into the upcoming clash with Manchester City with some added confidence.