Kai Havertz came off the bench to haunt his former club, scoring a 97th-minute winner against Chelsea to send Arsenal into the Carabao Cup final.
The Gunners secured a 1-0 victory on the night at a rain-soaked Emirates, progressing 4-2 on aggregate over the Blues.
Mikel Arteta’s side will now head to Wembley on 22 March, chasing their first League Cup trophy since 1993.
Chelsea boss Liam Rosenior praised his team’s effort but admitted they lacked the "clinical edge" to overturn the first-leg deficit.
