Alexander Frei's two goals led Borussia Dortmund past Bayern Munich 3-2 when the Bundesliga resumed on Friday after a 40-day winter break.
The Swiss forward scored in the 19th minute, then leveled in the 57th in a match played in steady snowfall. Two minutes later, he set up Tinga's winner by heading a cross to the Brazilian.
Bayern let a 2-1 lead slip away in a setback for the defending champion's title hopes. Bundesliga leaders Bremen and Schalke can pull six points clear with wins this weekend.
"We've always said we want to be German champions," Bayern defender Philipp Lahm said. "The way we played today, we won't be."
Both of Frei's goals were near identical, with Brazilian midfielder Dede crossing from the left and Frei heading each in after outleaping Lahm, a Germany defender.
"The coach told me I can't play with my head very well -- I showed him differently," Frei said.
The home win, in front of 81,000 at Westfalenstadion, lifted Dortmund to sixth place and gave interim coach Juergen Roeber success in his debut.
Dortmund charged out and controlled the early going, but Bayern's Daniel van Buyten scored in the 25th and a defensive blunder gifted a go-ahead goal by Roy Makaay in the 36th.
Goalkeeper Roman Weidenfeller and Marc-Andre Krezka mixed up signals on a passback, allowing Makaay to slip in and knock the ball into an open goal.