Eastbourne Borough required extra-time and penalties to see off County League division one side Shoreham and book their place in the Sussex Senior Cup final.
The Sports were pushed all the way by the underdogs who compete four divisions below the Blue Square Premier.
It looked like a routine victory for Garry Wilson's men at the Three Bridges ground when Simon Wormull gave Boro the lead on 12 minutes.
But Shoreham refused to lie down and hit back when Darren Annis levelled on 28 minutes.
Boro dominated possession in the second half but despite all the their neat build up play they lacked a cutting edge and the game went to extra time.
Boro finally looked to have settled the tie in 117th minute when Nathan Crabb was bundled over in the box. Paul Armstrong took responsibility and scored his first goal since returning from a head injury.
But Shoreham were not finished and in the 120th minute they levelled when Lee Hook pushed a free kick onto the bar and the ball was headed home following a scramble.
Pat Harding got the penalties off to a good start for Eastbourne and Jamie Groves missed Shoreham's first spot kick. Armstrong, Jack Jeffrey and Matt Crabb all coverted from the spot before Danny Brown lashed home the decisive kick.
Boro will face Brighton reserves in the final to be played at Priory Lane.