Having knocked out Bundesliga opposition in the previous three rounds, the hosts were no unknown quantity for Xabi Alonso’s men, but the men from Westphalia came from behind to lead at half-time.
A quiet opening quarter of an hour abruptly ended when Jonathan Tah tapped home from close range, having been left unmarked when a corner was flicked on at the near post.
Unfazed by the setback and the gulf in status, Die Blauen hit back immediately as Piero Hincapié’s block was in vain, with the ball falling kindly to Marius Worl, who drilled it low to draw level with Patrik Schick as the top scorer in this season’s DFB-Pokal.
Incredibly, that equaliser was the just the start of Leverkusen’s woes, as Noah Sarenren Bazee failed to capitalise on some Hincapie hesitation, with Lukas Hradecky diving low to deny the striker.
However, with the last touch of the first half, Arminia grabbed the lead to send the already-raucous home fans into delirium.
Louis Oppie’s free kick drifted to the back post, allowing Maximilian Grosser to steal in front of a struggling Hincapie and send his team into half-time with an unlikely lead.
Having never reached the final of the DFB-Pokal despite making four semi-final appearances, history was just 45 minutes away for Michel Kniat’s side, and despite the introduction of Bayer’s star striker Victor Boniface, the home side constrained their Bundesliga opponents.
With no attempts on goal for the visitors in the opening 15 minutes of the second half, it was Arminia who unexpectedly enjoyed the majority of possession and had control of the match, with Joel Grodowski missing a golden chance to put his team on the brink of a trip to Berlin.
Eventually, the away side forced Jonas Kersken into a save, as the Arminia goalkeeper scrambled across his goal to tip away a Nordi Mukiele header that was bouncing awkwardly towards the bottom corner.
Schick was the next, and ultimately final, player to test the nerves of the locals, as his header back across goal grazed the outside of the post. It was too little, too late for Leverkusen, who underperformed on the night and became the latest top-flight victim in Arminia’s magical march to the Olympiastadion.
Flashscore Man of the Match: Maximilian Grosser (Arminia Bielefeld)