After five league games, the home side are in ninth place with eight points, while Dortmund are in fifth place with 10 points after five matchweeks and are three points from first-placed Bayern Munich.
Match preview
Union Berlin lost 1-0 against Borussia Monchengladbach in their last match on September 28, a game in which they produced no big chances, had just 36% possession and conceded the winner in the 96th minute.
Manager Bo Svensson felt aggrieved with the officiating during his side's loss and criticised the length of time added on at the end of the second half, but also said that his team defended the goal poorly.
To Svensson's credit, his team's defeat last Saturday was the first time they lost in the last seven games, a period in which they won four and drew two.
While the hosts boast the second best defensive record in the division considering they have only conceded three goals, they have worryingly only scored on four occasions, the joint fewest in the league.
Union Berlin have won each of their last three games at home in the Bundesliga by a margin of one goal, though prior to these wins they lost the previous three at Stadion An der Alten Forsterein.
Opponents Dortmund brushed off their disappointing 5-1 defeat against Stuttgart on September 22 with a 4-2 victory against VfL Bochum on September 27 and a 7-1 win against Celtic in the Champions League on October 1.
Sahin's side were drawing 1-1 with Celtic after nine minutes, but Dortmund headed into the half-time interval leading 5-1.
Karim Adeyemi netted a first-half hat-trick and helped ensure that his team won their second game of their 2024-25 Champions League campaign.
Sahin insisted that BVB's 7-1 win has to be the benchmark for his team moving forward, and contrasted their performance on Tuesday with their defeat against Stuttgart.
Dortmund have now scored 24 times and conceded on seven occasions in their eight competitive matches this season, though they have only produced the sixth highest xG tally of the Bundesliga's 18 top-flight sides.
BVB have a poor away record in the league in recent matches given they have lost three and drawn one of their last four games, scoring just twice and conceding 12.
Union Berlin Bundesliga form:
Union Berlin form (all competitions):
W
D
W
D
W
L
Borussia Dortmund Bundesliga form:
Borussia Dortmund form (all competitions):
D
W
W
L
W
W
Team News
Union Berlin will be without goalkeeper Yannic Stein until late October due to a shoulder injury that has sidelined him since early August.
Striker Ivan Prtajin and right-back Josip Juranovic are not likely to feature until the middle of the month, while Kevin Volland is a doubt as a result of a knee injury.
Svensson will almost certainly continue to start goalkeeper Frederik Ronnow, and he may task centre-backs Danilho Doekhi, Kevin Vogt and Diogo Leite with marshalling the defence in front of Ronnow.
Borussia Dortmund will be unable to select hat-trick hero Karim Adeyemi until late October due to a hamstring injury, while Giovanni Reyna is scheduled to return in the middle of October.
Forward Donyell Malen is a doubt because of a fever, and these absences could see Sahin field Jamie Bynoe-Gittens, Julian Brandt and Julien Duranville behind striker Serhou Guirassy.
Emre Can could partner Pascal Gross in a double pivot in midfield in front of centre-backs Waldemar Anton and Nico Schlotterbeck.
Union Berlin possible starting lineup:
Ronnow; Doekhi, Vogt, Leite; Haberer, Schafer, Khedira, Rothe; Jeong, Hollerbach; Jordan
Borussia Dortmund possible starting lineup:
Kobel; Couto, Anton, Schlotterbeck, Ryerson; Can, Gross; Gittens, Brandt, Duranville; Guirassy
We say: Union Berlin 0-1 Borussia Dortmund
Union Berlin's resilient defensive displays this season could make them stubborn opponents for Dortmund, and it would not be surprising if the away side needed a later winner to take all three points.