Erik ten Hag currently has nine players out with knocks and it leaves the manager with no choice but to chop and change his line-up.
New signing Mason Mount has missed the last two games after picking up a hamstring injury and despite returning to training, he is still a doubt for the weekend.
Deadline day arrival Sofyan Amrabat is also expected to be made to wait for his Man United debut after pulling out of the Morocco squad with a knock.
But the real issue comes in defence.
Raphael Varane, Lisandro Martinez, Luke Shaw and Tyrell Malacia are all out injured.
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Martinez is the only one of the four defenders to be close to fitness ahead of the Brighton game with the rest definitely out.
The Argentine didn't feature for his country over the international break and is now facing a late fitness test.
If he starts, he will likely be partnered by Harry Maguire who continues to struggle for form.
But if he isn't fit to play, United's centre-back pairing will likely be Maguire and Jonny Evans.
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And that is a sight that will delight Brighton's attack with the duo far down Ten Hag's defensive pecking order.
The Seagulls are the Premier League's top scorers, netting 12 goals in four games so far this season and they will be eyeing more at Old Trafford.
Manager Roberto De Zerbi will fancy his chances of coming away with three points as his side boast a brilliant record against United.
Brighton have won their last three league games against the Red Devils, thriving in the fixture in recent years after only winning three of their last 17 clashes beforehand.
They have become somewhat of a bogey team for United over the last couple of seasons and they will be aiming to continue that run this weekend.
And if Brighton do come out on top on Saturday, they will join an exclusive group.
Only Manchester City and Liverpool have ever registered four consecutive Premier League wins against United.
The Reds did so from 2000 to 2002 while City achieved the feat from 2013 to 2014.
This means Brighton can become the first team to claim four wins on the trot against United for nine years.
Ten Hag's side are currently on an impressive run at home though, so it will still prove to be a tough task.
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United have won their last eight games at Old Trafford, last going on that run under Sir Alex Ferguson in 2013.
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