Bremen snatched the playoff spot from Fortuna Dusseldorf on the final weekend of the regular season, while Heidenheim finished third in the 2.Bundesliga to earn the right to battle for a spot in the top flight.
Bremen finished eighth in the Bundesliga last season and have not actually operated outside of Germany's top flight since the 1980-81 campaign, which is an indication of just how much of a surprise it would be to see the club drop into the second tier for next term.
For some time, it did appear that Florian Kohfeldt's side would be sinking automatically into the 2.Bundesliga, but a thumping 6-1 win over Koln on June 27 saw them snatch the playoff spot from Dusseldorf, who were immediately relegated alongside Paderborn.
There is no getting away from the fact that it has been a disappointing campaign for Die Werderaner, but they are the huge favourites to overcome Heidenheim over two legs, with the second match set to take place on Monday night.
Only Paderborn (22) lost more Bundesliga matches than Bremen (19) during the 2019-20 campaign, though, while the Green and Whites had the second-worst record in Germany's top flight with just nine points from 17 matches, which will certainly hand the visitors confidence ahead of the first leg.
Heidenheim, as mentioned, finished third behind Arminia Bielefeld and Stuttgart in the 2.Bundesliga this season to earn the right to take on Bremen in a two-legged playoff affair.
The second-tier outfit won 15 of their 34 league matches, suffering just nine defeats in the process, but they will enter this match off the back of a 3-0 loss to Arminia Bielefeld last weekend.
Heidenheim have never played in the Bundesliga and were operating in the third tier as recently as 2013-14, and it would be some story if they managed to overcome Bremen to advance to the top level.
Bremen Bundesliga form: LLWLLW
Heidenheim 2.Bundesliga form: WLWDWL
Bremen will be without the services of Kevin Vogt due to suspension, meaning that there could be a spot at the back for Christian Gross, but it is otherwise expected to be the same side that started against Koln.
Bremen possible starting lineup:
Pavlenka; Gross, Veljkovic, Moisander; Gebre Selassie, M. Eggestein, Klaassen, Friedel; Osako, Fullkrug, Rashica
Heidenheim possible starting lineup:
Muller; Busch, Mainka, Beermann, Fohrenbach; Schnatterer, Griesbeck, Dorsch, Mohr; Otto, Kleindienst
We say: Werder Bremen 2-0 Heidenheim
Heidenheim will be determined to pull off a shock result on Thursday night, but it is difficult to back against Bremen, who were excellent against Koln last time out. The home side have a lot of talent in the final third and should have too much for the second-tier outfit, who must stay in the contest ahead of the return fixture.