The Portuguese boss is going to be on the touchline aiming to start on the right foot after a successful interim spell under Ruud van Nistelrooy.
Van Nistelrooy went unbeaten in his short stint after taking over from Erik ten Hag and steadied the ship for Amorim's arrival.
Man United are still 13th in the Premier League though following their worst-ever start, leaving them desperately in need of points to rise up the table.
Their opening game under a new regime comes against Ipswich who stunned Tottenham to claim their first top-flight win before the international break.
Kieran McKenna, who used to be a Red Devils coach, also worked at Spurs and will be eyeing another scalp against his former employers.
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Ipswich vs Man United: Amorim's first line-up
Amorim has a few big decisions to make in his first game at Man United and he could be set to experiment.
The first of his decisions comes in defence as he has multiple injuries to deal with.
He is known to play a 3-4-3 formation and there are no signs of him moving away from that, as he taught the system in his first training session on Monday.
But that means he needs three centre-backs and with Harry Maguire injured and Victor Lindelof a doubt along with Lisandro Martinez, his options are limited.
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Lindelof hobbled off for Sweden at the weekend and Martinez was sent home by Argentina with a back issue.
Matthijs de Ligt will start and it's likely Jonny Evans will have to come in too while in that third spot, Leny Yoro could finally be set to make his debut.
Yoro is yet to appear for United after suffering a serious foot injury in pre-season, but the £52million teenager has been back in training and could be ready to feature.
Luke Shaw could also be an option in a back three when he's fit and he trained there in Amorim's first training session at the club.
Behind the defence, Andre Onana will of course be in goal, as Diogo Dalot and Noussair Mazraoui prepare to take up roles further up the pitch at wing-back.
However, an unusual pick in Antony could be set to play there, with Amorim working with him at right wing-back on Monday.
It's yet to be seen whether he has trained in that position since, but it may be a move the Brazilian won't be keen on.
He provided a very frustrated reaction last season when being told to play at left-back by Ten Hag against Liverpool in the FA Cup.
But Amorim must see him as a contender to play that role along with Dalot and Mazraoui.
Kobbie Mainoo returned to training this week but hasn't played a single minute since October 6 due to injury so a midfield pairing of Manuel Ugarte and Casemiro is expected.
However, Mason Mount and Christian Eriksen will be hoping to impress Amorim in his early days to break into his best line-up eventually.
And Man United fans think Mount's career could be boosted under the new boss after he was heard being praised in training footage released earlier this week.
The former Chelsea man looked to be training in an advanced role behind the striker, which is where Bruno Fernandes will also be slotting into this system.
Fernandes is sure to start but now with Mount impressing too, Amorim has a very tough decision to make...
Marcus Rashford, Alejandro Garnacho and Amad Diallo have been competing for two starting spots for the majority of the season.
It now looks like they'll only have one to fight over from now on as their new manager won't be playing with out-and-out wingers.
Rashford has failed to regain any form this campaign while Garnacho has been criticised too, leaving Amad as potentially the best option.
He played in a more central role while on loan at Sunderland and earned rave reviews from his former Black Cats boss Tony Mowbray.
As well as that, he's also been in great form and Amorim played him in one of these roles in training on Monday afternoon.
Up front, Rasmus Hojlund will likely be the Viktor Gyokeres of this system at Man United, as Joshua Zirkzee challenges him for a start.
Rashford could also be a contender to start up front, as he led the line during a practice drill at Carrington this week.
Of course, not all international players had returned to training with Amorim, including Hojlund, but the England international may be handed a new position to try and refind some form.
Manchester United won their last away league game against Ipswich (1-0 in April 2002). Only once in their league history have they won consecutive visits to Portman Road, doing so in 1962/1963.
This will be Rúben Amorim's first match in charge of Manchester United. Aged 39 years and 302 days on the day of this game, he's the youngest to take charge of his first match for the Red Devils since Wilf McGuinness in August 1969 (31y 288d).
Ipswich vs Man United: What has been said?
Amorim has already revealed what Man United fans can expect to see in his first game in charge on Sunday.
Speaking to the club's website, he said: "I think you will see an idea. You could like it or not, I don't know, but you will see an idea.
"You will see a positioning. You will see something that we want to reach that kind of level. You will feel that.
"We have to know that it's like two trainings before the first match. This is the best league in the world.
"But if I have to say something to you, [it's that] you will see an idea. This I can guarantee."
He added: "The most important thing for me, at this moment, is to create the principles, the identity and the character that we had in the past."
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After their first Premier League win of the season last time out away to Tottenham, Ipswich are looking to earn back-to-back wins in the competition for the first time since February 2002 (a run of four that started with a 2-1 win against Tottenham).
Manchester United's Bruno Fernandes has made 137 passes which have broken the opposition's offside line in the Premier League this season, at least 15 more than any other player.
Ipswich vs Man United: How to follow
This Premier League clash will take place on Sunday, November 25.
Kick-off at Portman Road is scheduled for 4:30pm.
The game will be broadcast live on Sky Sports Main Event and Sky Sports Premier League. You can sign up to Sky Sports here.
talkSPORT will also keep you up to date with all the latest news and reaction.
To tune in to talkSPORT or talkSPORT 2 through the website, click HERE for the live stream.
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You can also listen via the talkSPORT app, on DAB digital radio, through your smart speaker and on 1089 or 1053 AM.
Meanwhile, talkSPORT.com will have live updates of the game on our dedicated live blog.