Bayern Munich overran a hapless Borussia Dortmund to win 4-2 in Der Klassiker on Saturday, as three goals in the opening 23 minutes helped them reclaim top spot in the Bundesliga and hand new coach Thomas Tuchel a winning start.

The Bavarians, who face Manchester City in the Champions League quarterfinals on April 11, were in ominous form as they went back into top spot on 55 points, leaving Dortmund two behind in second place with eight matches remaining.

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With Tuchel, who also coached Dortmund from 2015-2107, having replaced Julian Nagelsmann on the Bayern bench, the hosts were all over their title rivals from the start.

They went in front thanks to Dortmund keeper Gregor Kobel's 13th-minute howler when he completely miskicked his attempt to clear a Dayot Upamecano punt from the Bayern half and saw the ball roll into the net for an own goal.

Before Dortmund managed to regroup, Bayern scored again with Thomas Muller turning the ball in with his hip at the far post after a Joshua Kimmich corner was headed on by Matthijs de Ligt in the 18th.

Kobel's comeback from a five-week injury break turned into a complete nightmare five minutes later as he punched a Leroy Sane shot into the path of Muller to score an easy tap-in that left the Dortmund players in complete disbelief.

The visitors' ordeal was not over, with Bayern scoring seemingly at will and Kingsley Coman racing in to slot in their fourth goal six minutes after the restart.

With Dortmund's defence torn to shreds and club bosses frozen in their seats at the Allianz Arena, Bayern never took their foot off the gas.

Some sloppy finishing, however, saw them squander half a dozen golden chances in the second half before Dortmund struck twice late in the game, with an Emre Can penalty in the 72nd minute and a stoppage-time effort from Donyell Malen.

Tuchel, who previously also coached Paris St Germain and Chelsea, could not have dreamt of a better start with Bayern on course for a record-stretching 11th league crown.

Union Berlin are third on 51 after a 3-0 win over VfB Stuttgart.