While the hosts are hoping to end the campaign inside the top four, the visitors are merely playing for pride having already secured their top-flight status for 2023-24.
Match preview
Four year ago, Union Berlin secured promotion to the Bundesliga for the first time after winning the second-tier playoffs. Fast-forward to the present day and they are on the cusp of creating more history as they are potentially just one win away from securing a top-four finish.
The Irons Ones have got to this stage the hard way, though, having lost two and drawn one of their last four Bundesliga matches, including a 4-2 away defeat against relegation-threatened Hoffenheim last weekend.
With Hoffenheim leading the thrilling contest 3-1 heading into second-half stoppage time, Danilho Doekhi pulled one back in the 95th minute to give the visitors hope, but the hosts regained their two-goal cushion courtesy of a 99th-minute strike from Mu'nas Dabbur.
Despite only winning four of their last 13 Bundesliga matches, Urs Fischer's side are clinging onto fourth spot on goal difference, with fifth-placed Freiburg - who play Eintracht Frankfurt on the final day - reducing the gap following their 2-0 win over Wolfsburg.
Union Berlin simply need to better Freiburg's result on Saturday to secure fourth spot and qualify for next season's Champions League, and they will be confident of claiming a positive result against Werder Bremen having won each of their previous four home meetings with the River Islanders in the top flight.
The Irons Ones are also the only Bundesliga team who are yet to lose on home soil this season having won 10 and drawn six of their 16 matches at Stadion An der Alten Forsterei, conceding the fewest home goals (11) in the process.
A European push was not out of the question for Werder Bremen earlier this year as they were sitting in eighth place in the Bundesliga standings in early February.
However, the River Islanders have been in free-fall since then, slipping down to 12th place following a torrid run of just two league wins in their last 14 matches, conceding 25 goals in the process.
Fortunately for Ole Werner, his side ended a losing run of three games with a 1-1 draw at home to Koln last weekend, a result that has secured their top-flight status for a 59th season; only Bayern Munich can match that tally.
Steffen Tigges put the visitors in front midway through the first half, but Bremen restored parity courtesy of a 73rd-minute strike from substitute Romano Schmid to ensure that the River Islanders remain four points above the bottom three with just one game remaining.
While the pressure is off Bremen heading into the final day, Werner will be keen for his side to avoid ending the campaign on a whimper and will endeavour to lead the River Islanders to their first away win over Union Berlin since a 2-1 success in September 2019.
Union Berlin Bundesliga form:
D
W
D
L
W
L
Werder Bremen Bundesliga form:
L
W
L
L
L
D
Team News
Union Berlin's only injury absentee is midfielder Andras Schafer who is suffering from a reoccurring foot problem.
However, key centre-back Robin Knoche is set to return to the starting lineup on Saturday after missing last weekend's defeat against Hoffenheim through illness, with Paul Jaeckel the unfortunate one expected to make way.
Top scorer Sheraldo Becker contributed to all four goals in Union Berlin's last home game, scoring twice and providing two assists in a 4-2 win over Freiburg, and the Dutchman is expected to lead the line alongside Kevin Behrens, who was also on the scoresheet in the last home match.
As for Werder Bremen, Felix Agu (patella tendon), Christian Gross (knee), Amos Pieper (ankle), Dikeni Salifou (foot) and Mitchell Weiser (muscle) are all sidelined due to injury, while Jens Stage is suspended following an accumulation of yellow cards.
The absence of ever-present midfielder Stage is set to see Niklas Schmidt recalled to the first XI to start alongside Ilia Gruev and Leonardo Bittencourt, while last weekend's goalscorer Schmid will likely replace the injured Weiser at right wing-back.
Niclas Fullkrug is the Bundesliga's top goalscorer this season, sitting two goals clear at the top of the charts after netting 16 goals in 27 games; the German is set to start on Saturday and is hoping to become the first Werder Bremen player since Miroslav Klose in 2005-06 (25 goals) to win the Golden Boot.
Union Berlin possible starting lineup:
Ronnow; Doekhi, Knoche, Leite; Trimmel, Laidouni, Khedira, Haberer, Roussillon; Becker, Behrens
Werder Bremen possible starting lineup:
Pavlenka; Veljkovic, Stark, Friedl; Schmid, Bittencourt, Gruev, Schmidt, Jung; Fullkrug, Ducksch
We say: Union Berlin 3-1 Werder Bremen
Despite their recent wobble in form, Union Berlin will be regarded as favourites to come out on top against a Werder Bremen side who have been struggling to grind out positive results for some time.
Fischer is sure to have a constant eye on Freiburg's result throughout Saturday afternoon, but as long as his side can claim a victory, preferably a convincing one, they should do enough to book their place in next season's Champions League.