Dortmund's midfielder Sebastian Kehl (C) lifts the trophy next to teammates and German President Joachim Gauck (R)
Bundesliga champions Borussia Dortmund blasted Champions League finalists Bayern Munich 5-2 in Saturday's German Cup final to claim the first domestic double in their 103-year history.
Poland striker Robert Lewandowski netted a hat-trick in the rout which will dent Bayern's confidence ahead of next Saturday's Champions League final against Chelsea at Munich's Allianz Arena.
"We cannot complain. Our entire defensive play was a catastrophe," admitted Bayern coach Jupp Heynckes.
"We have to take the blame and we did not deserve to win. We still have a major goal in mind and I think we will have all recovered from the shock by the Champions League final. That will be a completely different game."
After winning the German league title by eight points from Bayern, Dortmund continued their domination with their fifth consecutive win against Munich in the sold-out final at Berlin's Olympic Stadium.
Unbeaten in their last 23 games in all competitions since last December, Dortmund have yet to lose in 2012.
"That was a cup final which no one from Dortmund could have better imagined," beamed Dortmund coach Jurgen Klopp after his first cup win.
"We were ice cool in our finishing and scored great goals. It's hard to put into words what has happened to us."
Goals by Japan star Shinji Kagawa, a penalty from Germany defender Mats Hummels and Lewandowski's treble cancelled out Arjen Robben's first-half penalty for Bayern and a second-half strike from France's Franck Ribery.
Dortmund drew first blood after only three minutes in the wake of a mistake by Bayern defender Luiz Gustavo which allowed Poland midfielder Jakub 'Kuba' Blaszczykowski to square for Kagawa to fire home.
Bayern looked nervous in defence and Ribery was well chaperoned down the left flank with a posse of Dortmund defenders waiting to snuff out any threat whenever the ball arrived at his feet.
But Munich drew level after Mario Gomez was tripped by Dortmund goalkeeper Roman Weidenfeller as they both sprinted for the ball and Robben sent the Borussia captain the wrong way to fire home on 25 minutes.
It was redemption for Robben who missed a penalty in last month's German league showdown which Dortmund won 1-0.
Weidenfeller came off injured on 32 minutes after his clash with Gomez to allow Australian goalkeeper Mitchell Langerak to take over for only his fifth game of the season.
Borussia regained the lead with 41 minutes gone when when Kuba was brought down by Bayern defender Jerome Boateng and Hummels fired home the resulting penalty.
Dortmund added to their tally in added time when Kagawa played in a beautiful pass to the feet of Robert Lewandowski which allowed the Poland striker to make it 3-1 at the break.
Dortmund drove the nail further in Bayern's coffin when a pass from Grosskreutz found Lewandowski unmarked in the area and he fired home on 58 minutes.
Things went from bad to worse for Bayern as Gomez rattled the crossbar with a header with 20 minutes left, before Ribery reduced the deficit with a well-taken strike on 75 minutes.
Germany's number one goalkeeper Manuel Neuer capped a poor night in Bayern's goal when he lost possession to allow Lewandowski to head his third goal nine minutes from time and claim his 30th goal of the season in all competitions.