The sides that come ninth to 24th will compete in the two-legged knockout play-off ties in February and there could be two British sides involved.
Forest fell to a 1-0 defeat by Braga in Portugal, a result that practically confirms Sean Dyche’s side will be in the play-offs.
Mathematically, Forest, in 16th, can still finish eighth, but would need to beat Hungarian team Ferencvaros at the City Ground and hope the eight sides directly above them all dropped points.
However, Forest will still be keen to win next Thursday as the sides coming ninth to 16th will play the second legs of their knockout play-off ties at home.
Celtic were 2-0 ahead against Bologna, but down to 10 men, before the Italians fought back to earn a 2-2 draw. However, the point leaves Martin O’Neill’s side on eight points and occupying 24th spot, the last of the play-off places.
They will guarantee a top-24 position if they beat Dutch side Utrecht at home, but are likely to be out if they drop points.
“We’ve given ourselves a chance – that’s all, a chance – of qualifying and from that viewpoint, I’m delighted,” said O’Neill.
Rangers secured their first win of the league phase by beating Bulgarian side Ludogorets 1-0 but they are still eliminated after picking up just one point from their opening six games.
Danny Rohl’s side are 31st and next go to Portugal to face a Porto side aiming to finish in the top eight.
Rangers are one of six sides who cannot make the play-offs, along with Sturm Graz, Nice, Utrecht, Malmo and Maccabi Tel Aviv.
But every one of the 18 matches to be played on the final day has something riding on it.