Heidenheim came from two goals down to force a 2-2 draw at home to Elversberg in the first leg of their Bundesliga relegation playoff on Thursday.
Elversberg, who have never played in the top flight and are in just their second Bundesliga 2 campaign, ran out to a 2-0 half-time lead thanks to goals from Lukas Petkov and Fisnik Asllani.
Heidenheim fought their way back into the match and the tie with two goals in four second-half minutes through Tim Siersleben and Mathias Honsak.
"A brutal game," Heidenheim coach Frank Schmidt told Sky Germany.
"We're in a good situation to go to Elversberg next week. Everything is open for the return leg."
Elversberg coach Horst Steffen was not too discouraged despite watching his team surrender a two-goal lead.
"At the end it's alright, we wanted to avoid defeat. We'll have to get it done at home," said Steffen.
The winners of the playoff, between the side third last in the Bundesliga and the third-placed Bundesliga 2 team, will play in the top flight next season.
Elversberg, from a town of just 13,000 people, are bidding to become the smallest club to play in the top flight. They took the lead after 18 minutes when Petkov finished off a fluid team move.
Asllani doubled the visitors' advantage just before half-time, cutting the ball in from just inside the box.
Heidenheim reacted by bringing Bayern loanee Paul Wanner, who spent last season on loan at Elversberg, off the bench for the second half.
Siersleben gave Heidenheim hope when he tapped in a rebound from a Leo Scienza free-kick on 62 minutes.
Wanner then linked up with Scienza whose low shot was saved but bounced into the path of Honsak. He tapped home to give his side hope ahead of Monday's second leg in Elversberg.
Since the Bundesliga playoff was reintroduced at the end of the 2008-09 campaign, the top-flight team has won over two legs in 13 of 16 seasons.
The most recent second-division side to win promotion via the playoff was Union Berlin, who came through on away goals against Stuttgart in 2019.
