The visitors got themselves off the mark in the Europa League on Thursday night and will hope to remain top of the table going into next week.
Match preview
After only avoiding the relegation playoffs by goal difference last season, it has not been the start to the new campaign that head coach Pellegrino Matarazzo would have wanted at Stuttgart.
Die Roten drew five of their first six matches of the season in a strange opening period, but two successive defeats to Eintracht Frankfurt and Wolfsburg have left dark clouds hanging over the club.
Indeed, Yannick Gerhardt's last gasp winner for the Wolves at the Volkswagen Arena last weekend has left Matarazzo's side in the bottom three, and they may need to find a victory if they are to avoid falling into the automatic relegation places given that Bayer Leverkusen could leapfrog them by beating Schalke 04 earlier in the weekend.
However, finding their first league win of the season is unlikely to come remotely easily against a team who have won the joint most games (five) in the division so far this season, even if Matarazzo may take solace from his team managing to find the back of the net in four successive matches heading into the encounter.
Despite falling to a 2-0 defeat away to Frankfurt last weekend, Union Berlin remained ahead of Freiburg on goal difference to sit top of the Bundesliga heading into matchday nine.
The Iron Ones found their first win in Europe on Thursday, too, with the in-form Sheraldo Becker bagging a second half winner away to Malmo even after Andras Schafer had been given his marching orders on the stroke of half-time.
When Urs Fischer's side find themselves ahead they rarely drop points, let alone end up losing, with their defensive solidity and potency in transition making them a team to be feared on current form.
Union Berlin may find themselves leapfrogged by Freiburg, Bayern Munich or Borussia Dortmund - with the latter two facing off in Der Klassiker on Saturday - ahead of kick-off in Stuttgart on Sunday, so they are likely to be even more motivated than ever to get back to winning ways on the domestic front.
Stuttgart Bundesliga form:
L
D
D
D
L
L
Union Berlin Bundesliga form:
W
W
D
W
W
L
Union Berlin form (all competitions):
W
L
W
L
W
W
Team News
Stuttgart only have Josha Vagnoman out through injury at present, minimising the amount of excuses Matarazzo can have for his team's winless start to the season.
Despite the sale of Sasa Kalajdzic to Wolverhampton Wanderers in the summer transfer window, scoring goals has not been a problem for the hosts of late, but the American is likely to revert to a back five with the influential Borna Sosa coming in at left wing-back.
Union Berlin, meanwhile, will travel without Timo Baumgartl and Tim Maciejewski after the duo tested positive for COVID-19, while Kevin Mohwald is ruled out with a knock.
Schafer's dismissal in Sweden on Thursday is unlikely to have done himself any favours in terms of finding a starting spot in central midfield in league action, but Robin Knoche will almost certainly return to the heart of the defence after being a key part of gaining an away clean sheet in spite of Schafer leaving his side with a numerical disadvantage for more than 45 minutes.
Stuttgart possible starting lineup:
Muller; Mavropanos, Anton, Ito; Fuhrich, Endo, Karazor, Ahamada, Sosa; Guirassy, Silas
Union Berlin possible starting lineup:
Ronnow; Jaeckel, Knoche, Leite; Ryerson, Thorsby, Khedira, Haberer, Giesselmann; Becker, Siebatcheu
We say: Stuttgart 0-1 Union Berlin
We can envisage an extremely tight affair in Stuttgart, with both teams having plenty to lose ahead of kick-off.
However, Union Berlin are in much better form at present and are far more capable of holding onto a lead, which we expect them to do on Sunday.