Chester are through to face Scunthorpe United after they won at Kidderminster.
The Seals progress and are within 90 minutes of ending their National League exile after Declan Weeks returned to haunt the Harriers.
Scoring the winner against his old club eight minutes from time, Chester completed the turn around after trailing to Kyle Morrison’s goal.
Calum McIntyre’s team drew level through Dylan Mottley-Henry - and then went on to win it, sending the away supporters into pandemonium.
There was delight for the first time this season for the travelling fans at Eastbourne Borough.
That’s because Maidstone United did what nobody else has and won at Priory Lane - and they did it in dramatic fashion.
The Stones went ahead after 42 minutes.
Poking his team in front, Jacob Berkeley-Agyepong struck just before half time.
But the pendulum swung. Alfie Pavey made it 1-1 with a good finish before the visitors went down to ten men when Charlie Seaman was red carded.
But there was a huge twist when Aaron Blair grabbed a 90th minute winner to set up a final with Boreham Wood.