Bayer Leverkusen let a one-goal lead slip to lose 2-1 at home to Hoffenheim in new coach Erik ten Hag's Bundesliga debut on Saturday.
Taking over from Xabi Alonso in the summer and overseeing a radically restructured side after several high-profile exits, the former Manchester United boss cut a frustrated figure on the sideline.
Leverkusen hit the lead after six minutes when Jarell Quansah, who arrived from Liverpool this summer, headed in an Alex Grimaldo free-kick.
Hoffenheim, who finished just one spot above the relegation placings last season, levelled with 25 minutes played, Fisnik Asllani taking advantage of a defensive error from Quansah.
Tim Lemperle put the visitors ahead after 52 minutes. He was given too much time by Leverkusen's defence and skidded a low shot into the corner of the goal.
Leverkusen lost just three league games in the past two seasons, often saving points with the clock winding down, but there would be no late heroics. The defeat showed the scale of the rebuild Ten Hag has on his hands.
"Of course we're disappointed, that's clear... We've still got a lot of work to do. That's not unexpected," Ten Hag told reporters.
"I know from my experience the harder you work, the faster it goes, but we need to stay calm."
DORTMUND COLLAPSE
Borussia Dortmund gave away a two-goal lead with five minutes remaining to collapse to a 3-3 draw at St Paul, losing debutant centre-back Filippo Mane to a red card.
In the box seat for an opening-day win at 3-1 after goals from Serhou Guirassy, Waldemar Anton and Julian Brandt, Mane gave away a penalty and was sent off in the 85th minute for holding Abdoulie Ceesay in the box.
After Daniel Sinani converted from the spot, St Pauli went immediately on the attack and levelled things up just three minutes later, Eric Smith drilling a long-range effort into the top corner.
With 10 minutes of stoppage time awarded, the hosts looked the most likely to score, but Dortmund just held on, for a point.
"Last year we dropped a lot of points at the end due to red cards. It seems we've carried that into the new season," Brandt told Sky.
"It hurts. At some point, you have to stop explaining it to people afterwards and learn how to play with a man down in the important moments."
A first-half penalty miss from Guirassy with Dortmund a goal up also proved costly as Dortmund dropped points in a season opener for the first time in a decade.
Mane will miss Dortmund's next match and his absence is likely to hurt a side that has only one fit centre-back remaining in their squad.
Eintracht Frankfurt proved they still know their way to goal without departed striker Hugo Ekitike as they thumped Werder Bremen 4-1 at home, Jean-Matteo Bahoya scoring a brace in either half.
Now at Liverpool, Ekitike scored 15 and added eight assists in the league last season, but youngsters Bahoya, Can Uzun and Ansgar Knauff all scored for the home side in a dominant victory.
Bremen pulled one back through Justin Njinmah in the second half but rarely troubled the hosts.
German Cup holders Stuttgart were beaten by Union Berlin, who won 2-1 thanks to a first-half double from debutant Ilyas Ansah.
Back in Berlin for the first time since winning the cup final in May, Stuttgart hit the woodwork twice and had a stoppage-time equaliser for Nick Woltemade ruled out for offside.
Elsewhere, Augsburg won 3-1 at Freiburg and Wolfsburg won by the same scoreline at Heidenheim.
On Friday, defending champions Bayern Munich exploded in their season opener, beating RB Leipzig 6-0 at home, with Harry Kane scoring a second-half hat-trick.
