Takuma Asano scored a brace as Bochum won 2-1 at 10-man Darmstadt to claim their first victory of the Bundesliga season after 10 weeks of action.
Japan's Asano opened the scoring when he slotted into the bottom corner in the 25th minute and was on target again in the 54th on Friday.
Darmstadt got a temporary 43rd-minute equaliser from a Fabian Nürnberger header.
The hosts had captain Fabian Holland sent off with 20 minutes left for a last-man foul on Moritz Kwarteng, a week after teammates Klaus Gjasula and Matej Maglica were dismissed during an 8-0 defeat at champions Bayern Munich.
Bochum rose to 13th, while Darmstadt slipped to 15th and Union Berlin 16th and into the danger zone ahead of their Saturday game against Eintracht Frankfurt.
Union finished fourth last season but have lost their last seven league matches and 11 overall this term.
Saturday's big match is the duel between fourth-placed Borussia Dortmund and second-ranked champions Bayern Munich.
The two are unbeaten, and so are leaders Bayer Leverkusen who visit Hoffenheim.