Nottingham Forest can be considered as nearly nothing before this season because after promoting up to Premier League two seasons ago, they finished previous two seasons with postions from 16 to 17, that are surely not impressive ranks and only enough for them to seal the appearance in Premier League this season.
What they have done so far in Premier League this season are out of all expectation even their own expectation before this season start. Anyway the season is about remaining one-third of its length till its ending and Nottingham Forest actually have a good position and enough advantage to seal their appearance in top four or at least top five of Premier League. With highly chance of Premier League to have five slots for UEFA Champions League next season, Nottingham Forest have a perfect opportunity to participate in Champions League after several decades.
https://www.premierleague.com/clubs/15/Nottingham-Forest/season-historyYes, I also do not understand why Nottingham can perform so great surprisingly. Even though as we know Nottingham in the last few seasons is not a team that can be relied on and always struggles to avoid the relegation zone. But currently Nottingham is in the top standings in the English league, and what is even more surprising is that big teams like Manchester City have lost to Nottingham Forest. So the rapid progress that Nottingham Forest has is really great. But maybe the reason Nottingham Forest can perform like it is now is because the Nottingham Forest players already have good chemistry. So with that Nottingham Forest can perform well.
Then the second reason might be due to the purchase of a fairly large number of players made by Nottingham in the last summer transfer market. Because as far as I know Nottingham Forest was able to bring in more than 9 players in the last summer transfer market. One of them is Elliot from Newcastle and Nikela Milencovic from Fiorentina. Maybe because of this Nottingham Forest's performance can be as good as it is now. In addition, Nottingham Forest also has a great opportunity to appear in the Champions League next season. Because I am sure Nottingham Forest will definitely be able to maintain its current position until the end of the season.

And for the coming week Nottingham Forest will face Manchester United, I think with Nottingham's current performance Nottingham Forest will definitely be able to beat Manchester United.
Image Source: GoogleNottingham Forest will beat Manchester United hands down. Judging by the current records and performance of Manchester United this season,it's more convincing that the teams as a whole lacks confidence,no teams spirit and they overall playing pattern is poor and wouldn't give them an hedge against Nottingham Forest.
Surely Nottingham Forest will qualify to play in the champions league,they deserve it and I love to see them play and win more matches in the champions league. I am impressed with there Overall performance this season, and am sure if they can retain this current forms for the champion league, they will go far and make more progress.