The Poland international scored his 37th of the season with a deft touch to deflect a shot from Javi Martinez beyond Bernd Leno and into the net.
His effort arrived just three minutes into the DFB Pokal semi-final, which Bayern claimed by a 6-2 margin, with the poacher adding another shortly afterwards following a Franck Ribery cross.
“I know this trick from the scorers in ice hockey,” the 29-year-old admitted to Bild. “I’ve done it three or four times, getting a slight deflection to score. You need good timing, a good attitude and a good position.
“It makes it much more difficult for the opponents and especially the goalkeeper, a slight touch came make the difference for a goal.
“Jonathan Tah was right behind me and if I hadn’t touched the ball, he would have cleared it. Javi said afterwards that it was good I deflected the ball slightly.”
Lewandowski scored a similar goal for Borussia Dortmund against Bayern in April 11, beating Manuel Neuer with a similar deft touch. That was a crucial strike as BVB won the Bundesliga – the last time FCB were not top of the pile in Germany.
Although they have already claimed the Bundesliga title, they still have the DFB Pokal and Champions League to chase, with two big dates against Real Madrid looming in the semi-final of the latter competition.
Bayern will face Eintracht Frankfurt in the cup final on May 19, meanwhile.