Amorim will take charge of Sporting against Man City in the Champions League, in his penultimate game as head coach before taking over the job at Old Trafford.
Amorim's decision to join Man United comes just two weeks after City hired Viana, Sporting's director of football, to replace Txiki Begiristain at the end of the season.
Amorim revealed that he also thought about working at the Etihad Stadium, but the 39-year-old strategist affirmed that he was satisfied with the decision to join Man United.
"I made a decision and that's the club I wanted to work for. That's where I wanted to continue my coaching career. I don't deny that I thought about Man City, but I decided to choose the club I wanted to work for and nothing else. I wanted to move to Man United, that's the reality of what happened," Amorim said.
According to the previous announcement, Rubem Amorim will start work at Old Trafford on November 11. In the immediate future, he wants to defeat Pep Guardiola and Man City with Sporting Lisbon. In the Premier League, Amorim will continue to face Pep in the Manchester derby taking place on December 15.
Man City won a resounding 5-0 victory over Sporting Lisbon in the round of 16 of the 2022 Champions League.
"They played quite similar to what we faced two seasons ago, the pattern was very clear. They changed players but still had the same coach, the same spirit," Guardiola shared about his opponents.
Many Man United fans will likely be tuning in to the Sporting v City game to get an early look at the team's new manager.
However, Amorim has warned against judging his suitability for the Man United job based on just one game against Guardiola's side.
"The conclusions people draw from this game are not important to me. If I have a bad result against Man City then expectations will drop. If we win tomorrow people will think the new Alex Ferguson has arrived, it will be very difficult to meet that expectation.
I don't care what people say, what I care about is winning the game and then starting a new life in Manchester. We can have one situation or another, which can raise expectations. I don't know what is better for me," Amorim concluded.
