There are few teams in the Premier League that can be underestimated and Manchester United sometimes play quite well, another thing is that they are very bad in defense. And as for motivation, it seems to me that Nottingham's motivation for this match will be much higher, at least because they have a clear goal, it is the Champions League zone, and they are moving towards it well. And besides, Nottingham have won almost all their home matches in the Premier League, only a couple of draws and defeats.
Overall it is true that Nottingham Forest are much more superior, especially the match will take place at home so their motivation to win the match is much greater, especially since there is something they want to achieve in the Champions League. Nottingham Forest is one of the clubs that is quite surprising this season because they are able to play well to reach the top three positions in the standings.
That is different from Man United who this season has experienced a decline and they have lost their best form which is much worse than the previous season. But even so in this match it will not be so easy for Nottingham Forest to achieve victory because Man United themselves will also try to get points.