Bochum and Holstein Kiel were relegated from the Bundesliga on Saturday after defeats by Mainz and Freiburg respectively, though Heidenheim still have a chance of escaping the relegation play-off place.
Bochum, who had been promoted from the 2. Bundesliga in 2021, suffered a 4-1 home loss to European hopefuls Mainz, leaving them seven points adrift of 16th-placed Heidenheim with just one game remaining.
They went into Saturday needing a win to have any chance of staying up, but Mainz went in front in first-half stoppage time thanks to Nadiem Amiri's superb free-kick.
Phillipp Mwene struck eight minutes after the restart and Jonathan Burkardt made it 3-0 to extinguish Bochum's hopes.
Bochum cut the deficit through Gerrit Holtmann's low drive, but Pual Nebel scored for Mainz in stoppage time, with the visitors climbing to sixth in the table – which would bring Europa Conference League qualification.
Holstein Kiel, who won promotion last season, took a 24th-minute lead against Freiburg through Lasse Rosenboom, but the top-four contenders staged a fightback.
They levelled in first-half stoppage time through Johan Manzambi, before Lukas Hoeler headed in a second-half winner.
Freiburg are fourth on 55 points, with Borussia Dortmund – currently fifth on 51 – taking on Bayer Leverkusen on Sunday.
Heidenheim, meanwhile, could still avoid a play-off against the third-placed finishers from the 2. Bundesliga, having won 3-0 at Union Berlin.
Adrian Beck scored twice for Frank Schmidt's team, with Jan Schoppner also on target as they moved within two points of 15th-placed St. Pauli.
St. Pauli could secure survival with a win at Eintracht Frankfurt on Sunday, while Hoffenheim – 14th and three points clear of Heidenheim with a superior goal difference – are not yet safe with one game remaining.