Maximilian Mittelstaedt fired in for Hertha after three minutes before former Arsenal winger Serge Gnabry slammed home a half-volley.

Gnabry slotted in another but Hertha levelled through Davie Selke, who made the most of Matt Hummels' weak header.

Coman nodded in what proved to be the winner eight minutes into extra time.

Elsewhere, RB Leipzig reached the quarter-finals of the cup for the first time with a 1-0 win over Wolfsburg. A ninth-minute strike from Brazilian forward Matheus Cunha, 19, was enough to see off their Bundesliga rivals.

Schalke recorded a 4-1 home win over Fortuna Dusseldorf and Augsburg edged past second-tier side Holstein Kiel 1-0.

Hamburg, Paderborn, Heidenheim and Werder Bremen also all won to progress through to the last eight.