The contest is delicately poised following a goalless draw in the first leg on Thursday, and the home side will be looking to pull off a shock victory to earn promotion to the top tier.
Heidenheim 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, and showed their quality against Bremen in the first leg on Thursday night.
The Bundesliga side would have been looking to take a lead into the second leg, but Heidenheim defended impressively to ensure that they would pick up a positive result in their first encounter.
Heidenheim have never played in the Bundesliga and were operating in the third tier as recently as 2013-14, meaning that it would be some achievement if they managed to secure a position in the top flight.
Bremen have not played outside of Germany's top flight since the 1980-81 campaign, but they will be relegated unless they can overcome Heidenheim on Monday evening.
It did appear that Florian Kohfeldt's side would be sinking automatically into the 2.Bundesliga at the end of the regular Bundesliga season, but a 6-1 win over Koln on June 27 saw them snatch the playoff spot from Fortuna Dusseldorf, who were relegated alongside Paderborn.
Die Werderaner actually lost 19 of their 34 league matches during the 2019-20 campaign, conceding 69 times in the process - the second-worst record in the division behind Paderborn.
Bremen did perform much better on their travels, though, boasting the eighth-best away record in the Bundesliga, which is in contrast to their home record, which was the second-worst in the division.
Heidenheim form (all competitions): LWDWLD
Werder Bremen form (all competitions): LWLLWD
Konstantin Kerschbaumer, though, is also pushing for a spot in the starting side.
The visitors do not have any fresh fitness concerns, though, and Milot Rashica is again likely to be joined by Yuya Osako and Niclas Fullkrug in the final third of the field, leaving Joshua Sargent and Claudio Pizarro on the bench.
Heidenheim possible starting lineup:
Muller; Busch, Mainka, Beermann, Theuerkauf; Multhaup, Sessa, Griesbeck, Dorsch; Thomalla, Kleindienst
Werder Bremen possible starting lineup:
Pavlenka; Selassie, Vogt, Veljkovic, Friedel; Klaassen, Bargfrede, Eggestein; Rashica, Fullkrug, Osako
We say: Heidenheim 1-2 Werder Bremen
Bremen will feel that they should have won the first leg, but we still fancy them to get the job done on Monday night. The Bundesliga side have a lot of talent in the final third and while we are expecting a tight match, we believe that the visitors will emerge victorious, retaining their spot in the Bundesliga in the process.