They defeated Fareham Town 5-3 on penalties at Fratton Park after a stoppage-time leveller from Tom Jeffes had cancelled out Ethan Jones’ 23rd minute opener.
Deans keeper Ellis Grant saved Jones’ opening penalty in the shoot-out in front of the Fratton End.
The following nine penalties were converted, with Ethan Robb completing Horndean’s victory with his side’s fifth effort.
Tommy Scutt, Ben Anderson, James Crane and Blankson also scored from 12 yards past Creeksiders keeper Luke Deacon.
It was Fareham’s third successive shoot-out in the competition – they had previously beaten holders Gosport Borough and Fleetlands after 0-0 draws at Cams Alders.
1. Tom Jeffes about to score Horndean's stoppage-time leveller
Tom Jeffes about to score Horndean's stoppage-time leveller. Picture by Ken Walker Photo: Ken WALKER
2. Fareham players applaud their supporters
Fareham players applaud their supporters. Picture by Ken Walker Photo: Ken WALKER
3. Fareham's Josh Benfield, right, applauds the supporters
Fareham's Josh Benfield, right, applauds the supporters. Picture by Ken Walker Photo: -
4. Tom Jeffes scores Horndean's stoppage-time leveller
Tom Jeffes scores Horndean's stoppage-time leveller. Picture by Ken Walker Photo: Ken WALKER