The match ended in a goalless draw before the outsiders stunned Dortmund 4-2 on penalties.

Goalkeeper Robert Wulnikowski was the hero of the night as he saved two penalties from Lucas Barrios and Robert Lewandowski.

Elsewhere, Bundesliga leaders Mainz were also surprised by second-division Alemannia Aachen, who won 2-1 on Wednesday.

Hamburg and Bayer Leverkusen followed their Bundesliga rivals out of the cup after losing to Eintracht Frankfurt and Borussia Monchengladbach.