MUNICH (AP) -- Robert Lewandowski scored twice against his former club to help Bayern Munich return to form with a 4-0 rout of Borussia Dortmund in the Bundesliga's ''Klassiker'' on Saturday.
Dortmund defender Mats Hummels' own goal in the 80th minute of his first game back at his former club compounded the visitors' misery in their fifth consecutive heavy defeat in Munich.
Dortmund lost 5-0 in Munich in April, 6-0 last year, 4-1 in April 2017 and 5-1 in October 2015.
Lewandowski got the latest thrashing underway in the 17th minute, heading in Benjamin Pavard's cross after being left in plenty of space by the Dortmund defense.
It ensured the Polish striker stretched his Bundesliga record by scoring in each of the opening 11 games this season.
Bayern was hoping to send a signal in its first league game since firing Niko Kovac as coach on Sunday.
Kovac departed a day after the team slumped to a 5-1 loss at Eintracht Frankfurt, Bayern's heaviest Bundesliga defeat in over 10 years.
But Bayern looked a side reborn under interim coach Hansi Flick. The former Germany assistant started with a 2-0 win over Olympiakos in the Champions League on Wednesday and has now overseen two wins with no goals conceded.
''We're going to keep going with Hansi for the time being,'' chairman Karl-Heinz Rummenigge said after the gala display against Dortmund.
Bayern had to wait till the 47th before Serge Gnabry got the second goal, though he had to wait for VAR checks to confirm Thomas Muller was not offside.
Muller set up Lewandowski for his second goal in the 76th, the striker taking his tally to 16 goals in 11 league games.
Hummels' own goal came after he was pressurized by Thiago Alcantara and wrapped up another night to forget for Dortmund.
''We lost nearly every ball in the first 25 minutes, it wasn't good. Unbelievable. It was very poor from us,'' Dortmund coach Lucien Favre said.
''Bayern played much better than us. A lot of our players just weren't there today. That's the biggest disappointment.''
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