The hosts had led through Mario Kvesic’s goal but Damir Kreilach equalised for the visitors just before half-time. Haas then had a nightmare second half, caught in possession for Kreilach’s second, and then he was chipped by Simon Skarlatidis for the third.
The win takes Jens Keller’s side to second in the 2. Bundesliga table, five points behind leaders Eintracht Braunschweig.
Ost rivals both on back of 2-1 victories
Aue came into the game in 14th place after their last minute 2-1 victory over FC St. Pauli last weekend, which had ended a three-game winless streak. They were looking win another Ostderby, after victory against Dynamo Dresden last month.
They were forced into one change to the starting line-up, with Calogero Rizzuto replacing Nicky Adler, who went off injured at the Millerntor, however Christian Tiffert and Cebio Soukou also returned in place of Philipp Reise and Skarlatidis.
Union meanwhile have been living up to their status as dark horses, going in fifth and very much part of the pack trying to hunt down Braunschweig. They beat relegated Hannover 96 last time out, with only one defeat all season.
However Keller decided to ditch Union’s 4-3-3 in order to accommodate both Collin Quaner and Philipp Hosiner up front, with Kenny Prince Redondo making way for Quaner. Michael Parensen was ill and Felix Kroos had muscular problems, so Kristian Pedersen and Dennis Daube came in as well.
Aue in control but Kreilach brings Union level
The two strikers for Union combined early on, with Quaner setting up Hosiner for a shot, however it was saved by Haas, who was until the end of last season a Union player for four seasons.
However it was the hosts who had the better of the first half, with Kvesic particularly a threat, forcing Jakob Busk into two saves, one from distance and a free-kick wide on the left.
And it would be the Bosnian who gave them the lead. Fabio Kaufmann’s cross appeared to have bypassed everyone in the box, but it was picked up by Kvesic on the left, who despite having two defenders and Busk to beat managed to steer it in at the near post.
Aue remained on top through the quieter stages that followed, however a free-kick given away by Julian Riedel a few minutes before half-time on Union’s left proved costly. Daube took, it was headed on by Hosiner, who looked offside, Quaner volleyed into the post and Kreilach headed in the rebound to level.
Haas gifts his former side the win
Early in the second half Pascal Köpke had two great chances to restore the lead for his side. The first he should have scored, after Kvesic beat Busk with his cross, but he somehow shot over. The second was more difficult, with Emanuel Pogatetz challenging him, and he put the ball wide.
He would come to rue those missed chances when Union took the lead. A back pass from Tiffert should have been easy enough for Haas to deal with, but inexplicable he allowed himself to be dispossessed by his former teammate Quaner, who set up Kreilach, who simply had to place the ball into the empty net.
Kvesic had a great chance to equalise for Aue. Showing great skill in the box to control the ball, he unleashed a fierce strike towards goal, but Busk proved too much of an obstacle for him to beat.
And then it got worse for Haas. A great long ball from Kreilach found the substitute Skarlatidis, who caught the keeper out of his goal first a first-time chip into the back of the net.
From there Union simply had to see the game out, although Skarlatidis could have got a fourth on the counter, beating Haas but forced out by Steve Breitkreuz. The game was already won though.