The hosts, playing their first competitive game of 2025, started the brighter, but they didn’t seriously test visiting goalkeeper Frank Feller - making just his third-ever first-team appearance - until the 21st minute. An inviting ball in from Marcos López was met by fellow full-back Rodrigo Huescas and tipped onto the crossbar by Feller, with Jordan Larsson’s follow-up vitally cleared away by Norman Theuerkauf.
Copenhagen were still the more threatening side however as 18-year-old Victor Froholdt surged forward impressively, but his shot, although firmly struck and swerving a bit, was comfortable enough for Feller to deal with.
Home captain Viktor Claesson then proceeded to volley over from Huescas’ searching cross, but Copenhagen went in front on the stroke of HT as Magnus Mattsson’s slide rule pass released López, who showed good strength to hold off Marnon Busch before squaring for Larsson to turn home.
Heidenheim’s players and supporters must have had a familiar sinking feeling having lost their four games before this trip to Denmark, with head coach Frank Schmidt opting to bring on Omar Haktab Traoré for Theuerkauf at the break, and it was the newly introduced right-back who had the Bundesliga outfit’s first shot on target in the second half, albeit easy enough for Diant Ramaj to hold.
It wasn’t long before Heidenheim equalised though, as Huescas was penalised for a foul on Léo Scienza. Bayern Munich loanee Paul Wanner whipped the resulting free-kick into the box, and after it was met by headers from centre-back pairing Patrick Mainka and Tim Siersleben, Thomas Keller applied the finishing touch from close range.
Sensing blood, Schmidt threw on Mathias Honsak and Budu Zivzivadze for Sirlord Conteh and Marvin Pieringer, with Ramaj soon forced into a superb flying save by Wanner before brilliantly denying Honsak.
Copenhagen were now the side under pressure, but after appearing to have weathered the storm, substitutes Mohamed Elyounoussi and Elias Achouri combined, with the latter thwarted by the outrushing Feller as both teams targeted a win before the second leg in Germany.
But it was Heidenheim who dramatically snatched victory as the marauding Siersleben profited from a ricochet off Thomas Delaney to find Ramaj’s bottom left-hand corner with aplomb.
Heidenheim have now won four of their five European away games this campaign including qualifiers and return to league action against Mainz on Sunday with a spring in their step, while Copenhagen’s seven-match home unbeaten run came to a crushing end.
Flashscore Man of the Match: Tim Siersleben (Heidenheim)