Nottingham has proven their strength this season through the consistency they have shown throughout this season. And at this time I personally have no doubts that Nottingham will remain in its current position, namely 3rd place until the end of the season and secure the UCL ticket quite calmly and comfortably with Arsenal and Liverpool. Meanwhile, other teams will certainly compete fiercely for 4th place.
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For now, Nottingham is 6 points ahead of the nearest team, if you look at that I think they are still not comfortable in 3rd place and there is still a possibility that they will lose their place because in the remaining matches they will face strong teams so that losing points is still open for them. Aston Villa, Everton, Tottenham and Chelsea are not easy opponents to beat. But if it is to secure a UCL ticket, yes they have a great chance considering that there are 5 tickets that will be distributed in the Premier League.
Nottingham Forest faced a lot of huddle's before getting to that point, as it's stands now they are very formidable, so it's highly possible that they can maintain that position. Whatever inconsistent you feel they will face, also place it on Manchester City too as they are not going to get an easy ride too because even the least Club you didn't expect can disrupt your plans. I agree with that Nottingham Forest will qualify for the champions league as they've already positioned themselves in an advantageous position at the moment.