Uwe Neuhaus has been relieved of his duties as Arminia Bielefeld head coach with the club winless in five and only a point above the automatic drop zone in the relegation play-off spot.
Bielefeld lost 3-0 at Borussia Dortmund in Neuhaus' 77th and final competitive game at the helm.
Although only below the waterline on goal difference alone, Arminia have claimed just one point from their last five matches, conceding at least three times in each of them.
"Due to current developments, we made the mutual decision to bring forward a change in management we had already planned for the summer," explained Bielefeld sporting director Samir Arabi. "We are still convinced that our team has the necessary quality to achieve our sporting goal.
"With the change at a decisive stage in the season, we want to give the team a fresh impetus. We need maximum cohesion, and the leveraging of all potentials and a passion that is anchored in the core values of our club."
Neuhaus took the Bielefeld reins from Jeff Saibene on 10 December 2018. He steered the North Rhine-Westphalian outfit to a seventh-placed finish in his first season in charge, before guiding them back to the Bundesliga following an 11-year absence as 2019/20 Bundesliga 2 champions.
"We're really grateful to Uwe Neuhaus and [co-coach] Peter Nemeth for their committed work since taking over," read a club statement. "As head coach, Uwe Neuhaus took over the team in a difficult situation at the foot of the table, and took them from being threatened with relegation to the Bundesliga as champions, in the space of 18 months."
Bielefeld have 11 games to turn their season around, starting with Union Berlin at home on Sunday. The club will announce Neuhaus' successor in due course.
The 61-year-old is the second managerial casualty of Matchday 23 following rock-bottom Schalke's dismissal of Christian Gross.
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