Heiko Herrlich's men were beaten 1-0 by Bayern Munich in their midweek game, while Union lost by the same scoreline to fellow high-flyers RB Leipzig.
As the only team in the top flight to have taken zero points from their last three matches, Augsburg's position is becoming more precarious by the week.
Herrlich's side kicked off 2021 in optimal fashion with a 1-0 win at Koln, but they have since suffered three defeats on the bounce to Stuttgart, Werder Bremen and now Bayern Munich.
Robert Lewandowski's 13th-minute penalty was enough to separate the two sides on Wednesday evening, with Augsburg striker Alfred Finnbogason missing a spot kick of his own as his side's winless run on home soil stretched to seven matches.
Herrlich's men gave a good account of themselves in the second period but ultimately succumbed to their fourth defeat in a row at the WWK Arena, and that result leaves 12th-placed Augsburg four points clear of the bottom three after 17 matches.
Being able to boast a measly three wins from their last 15 Bundesliga matches is a major point of concern for Herrlich, whose side would do well to come away with something against a Union team mixing with the big boys.
A first defeat of 2021 is certainly no cause for panic, though, as Union's remarkable form throughout the season sees them firmly in contention for a spot in European competition.
Fischer's side may have seen their six-game unbeaten run in the league come to an end on Wednesday, but they remain in the top six heading into the second half of the campaign, and the 32 goals that the visitors have already notched up can only be topped by Bayern and Borussia Dortmund.
Union could find themselves down in seventh before the game kicks off depending on what happens in Friday's fixture between Dortmund and Borussia Monchengladbach, but having suffered just two defeats away from home all season, they are sure to feel confident about their prospects of making an immediate return to winning ways.
However, Augsburg stormed to a 3-1 win on Union's turf when the sides met back in September, and the visitors can only boast a solitary win from their last seven attempts against Fuggerstadter.
Augsburg Bundesliga form: WLWLLL
Augsburg form (all competitions): LLWLLL
Union Berlin Bundesliga form: DWWDWL
Union Berlin form (all competitions): WLWDWL
Augsburg's medical room is rather empty at the moment, with Jan Moravek edging closer to a return to action after resuming training over the past week.
However, this game is likely to come too soon for Raphael Framberger, but other than that the hosts are well-stocked for this game.
Changes could be afoot with Marius Bulter and Christopher Trimmel both likely to return to the XI, while Nico Schlotterbeck will hope to earn some minutes, having recently recovered from a long-term injury.
Augsburg possible starting lineup:
Gikiewicz; Oxford, Gouweleeuw, Uduokhai; Caligiuri; Khedira, Gruezo, Iago; Jensen, Vargas; Finnbogason
Union Berlin possible starting lineup:
Luthe; Knoche, Friedrich, Hubner; Trimmel, Gentner, Promel, Andrich, Lenz; Bulter, Awoniyi
We say: Augsburg 1-2 Union Berlin
Augsburg were perhaps unfortunate not to have taken something from their clash with Bayern, but another home game without a win will further sap the hosts' confidence. Herrlich's men are capable of making it a challenging afternoon for Union, but we still expect the away side to keep their European hopes alive with a slender win.
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