Dortmund are assured of a Champions League place and only have position play for, while Mainz are desperately fighting to move out of the bottom three before the curtain comes down on the 2023-24 season.
Match preview
After being thumped 8-1 by Bayern Munich on March 9, Mainz were languishing in 16th place with two points separating them from the relegation playoff spot and a sizeable nine-point gap between themselves and safety.
At that stage, Mainz's survival chances looked bleak, but they since embarked on a remarkable seven-game unbeaten run (W3, D4) to move into the relegation playoff spot, leaving them five points clear of 17th-placed Koln and just one point adrift of Union Berlin in 15th position.
Despite their recent upturn in fortunes, Bo Henriksen's side may be slightly frustrated by the fact they have had to settle for 1-1 draws in each of their last three outings against Freiburg, Koln and Heidenheim.
By the time Mainz kicks off against Dortmund, they may already be guaranteed to finish outside the automatic relegation places depending on the result of Koln's home meeting with Union.
However, they will still be keen to avoid a relegation playoff and continue their fine home form after winning three of their previous four matches in front of their supporters.
Unfortunately for Mainz, they have struggled in recent meetings with Dortmund at the Mewa Arena, losing seven of their last eight home encounters (D1) since recording a 2-0 win in September 2014.
Dortmund will head into the weekend in a celebratory mood after they claimed a 2-0 aggregate win over Paris Saint-Germain to secure a place in the Champions League final for the third time in their history.
Edin Terzic's troops recorded a narrow 1-0 win in the home leg, before veteran defender Mats Hummels scored the only goal of Tuesday's return fixture to become the oldest German player to score in a Champions League knockout match, ensuring Dortmund can continue to dream of winning UEFA's premier club competition for the first time in 27 years.
After losing to domestic rivals Bayern Munich at Wembley in their most recent European final appearance, die Schwarzgelben will return to the home of English football for next month's showdown against record-winners Real Madrid, who can call upon the talents of former Dortmund star Jude Bellingham.
Before they meet the Spanish giants on June 1, the German side will wrap up their Bundesliga campaign with an away game against Mainz and a home game against basement side Darmstadt.
Despite their success on the European stage, Dortmund have failed to meet expectations in the league, having collected 60 points from 32 matches to leave them in fifth place and three points adrift of the top four.
With the Bundesliga getting an extra Champions League place, die Schwarzgelben will have already secured their spot in next season's competition, but they will still be keen to creep into the top four and avoid their worst league finish since ending the 2014-15 season in seventh place.
Mainz 05 Bundesliga form:
D
W
W
D
D
D
Borussia Dortmund Bundesliga form:
W
L
W
D
L
W
Borussia Dortmund form (all competitions):
W
D
L
W
W
W
Team News
Stefan Bell has returned to training after recovering from myocarditis, but the Mainz defender is unlikely to be ready to feature in Saturday's home clash.
Maxim Leitsch remains sidelined with a groin problem, while Karim Onisiwo is a doubt after he missed the draw with Heidenheim through injury.
Nadiem Amiri and Brajan Gruda are set to return to the side following suspension, but Phillipp Mwene still has another game to serve on his two-match ban.
With Dortmund assured of Champions League qualification, Terzic is expected to make several changes following Tuesday's successful trip to the French capital.
Marius Wolf and Niklas Sule could come in to freshen up the backline, while Felix Nmecha is pushing for a place in midfield.
Marco Reus is also in contention to start his penultimate league game, before he ends his long association with Dortmund at the end of the season.
The 34-year-old could be joined in the Dortmund attack by Donyell Malen, Jamie Bynoe-Gittens and Youssoufa Moukoko after the trio started last Saturday's league win over Augsburg.
Mainz 05 possible starting lineup:
Zentner; Kohr, Van den Berg, Hanche-Olsen; Widmer, Barreiro, Amiri, Caci; Gruda, Lee, Burkardt
Borussia Dortmund possible starting lineup:
Kobel; Wolf, Sule, Schlotterbeck, Maatsen; Can, Nmecha; Malen, Reus, Bynoe-Gittens; Moukoko