Hamburg were thrashed 5-1 by Sandhausen on the final day of the 2. Bundesliga as they missed out on a promotion play-off, but Stuttgart are back in the top flight despite losing to Darmstadt.
Relegated from the Bundesliga for the first time back 2017-18, Hamburg needed to better Heidenheim's result to book a place in a play-off with Nordderby rivals Werder Bremen, who finished 16th in the top flight.
Heidenheim were beaten 3-0 by champions Arminia Bielefeld but Hamburg could not get the job done at home against mid-table opposition.
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Hamburg manager Dieter Hecking made two changes from the side who lost last Sunday to Heidenheim, with the injured Timo Letschert being replaced by Ewerton in the middle of defence
Jordan Beyer also took a place on the bench, as Gideon Jung moved into the back three, leaving space for Adrian Fein to move back into one of the two defensive midfield slots.