Bundesliga champions Bayern Munich suffered a title-party hangover Saturday with a shock 3-1 defeat at Mainz, while Erling Haaland claimed a hat-trick even though Borussia Dortmund crashed 4-3 at home to Bochum.

A week after Bayern beat second-placed Dortmund 3-1 in Munich to be crowned league champions for the tenth straight season, Germany’s top two clubs both lost.

Bayern boss Julian Nagelsmann was furious after his team’s lacklustre display at Mainz, who also hit the woodwork four times in a deserved victory.

“There are too many defeats, too many in the same manner,” Nagelsmann fumed.

“I think we always need a certain basic passion in our game, which we didn’t have today.

“To not go to the limit in every situation is human after the tenth title in a row, but we still wear the badge on our chest.”

Germany Under-21 striker Jonathan Burkardt and French defender Moussa Niakhate gave Mainz an early 2-0 lead after exploiting huge holes in Bayern’s defence.

The Bavarians pulled one back when Robert Lewandowski rolled in his 34th Bundesliga goal this season, claiming a league record after scoring 18 times away this campaign.

Midfielder Leandro Barreiro grabbed Mainz’s third goal just after the break when his shot took a wicked deflection and looped into the Bayern goal.

In Dortmund, Bochum raced into a 2-0 lead after just eight minutes thanks to goals by Sebastian Polter and Gerrit Holtmann.

Haaland led the fight back by converting two penalties, then tapped in his third goal with an hour played.

However, Bochum hit back with goals in the final ten minutes.

Juergen Locadia fired one in before Milos Pantovic converted the winning penalty after a handball by Dortmund midfielder Axel Witsel.

Bochum claimed their second significant scalp this year following February’s shock home win over Bayern.

– Home fans turn on Dortmund –

The Dortmund team trudged off to a chorus of whistles from home fans.

“I can understand that the fans are annoyed, but the lads didn’t deserve to be insulted like that,” said Dortmund coach Marco Rose.

“We are all mega disappointed.

“We reacted well after falling behind quickly, but when I look at the table and see 50 goals conceded (this season), it’s clear what the core issue is.”

Later, Freiburg climbed back into the top four and the Champions League places with a thrilling 4-3 win at Hoffenheim.

After Hoffenheim went 2-1 up early in the second half, Freiburg roared back with goals by captain Christian Guenter, Lucas Hoeler and South Korea’s Jeong Woo-yeong before Sebastian Rudy scored a late third goal for the hosts.

Cologne climbed to sixth and stay on course to play European football next season after a 4-1 romp at Augsburg with Anthony Modeste scoring twice.

Stuttgart kept alive hopes of avoiding relegation as midfielder Chris Fuehrich fired a late equaliser in off the crossbar to earn a 1-1 draw at home to Wolfsburg.

Stuttgart remain 16th, which carries a relegation play-off at the end of the season.

They have two tough games left – away to Bayern and home to Cologne – to bridge the four-point gap to 15th and guaranteed safety next season.

Hertha Berlin, who are four points and one place above Stuttgart, are not yet sure of avoiding relegation after a 1-1 draw at second-from-bottom Arminia Bielefeld.

Hertha were cruising to an away win thanks to a header by midfielder Lucas Tousart before Swedish defender Joakim Nilsson nodded in a last-gasp equaliser for Bielefeld.