Steve Claridge came off the bench to blast Gosport into the Southern League premier division after a 3-1 extra-time win at Poole.
Borough looked to be heading for a heart-breaking defeat in their south & west division one play-off final after falling behind to a first-half strike from Marvin Brooks.
But with just seconds left of normal time, Claridge rescued the visitors with an equaliser.
The former Pompey forward and manager was in the right spot at the right time to slot the ball into an empty net after Brett Poate’s initial shot was pushed back into his path by Hutchings.
Minutes into the first period of extra-time, Justin Bennett then showed his marker Michael Walker a clean pair of heels to blast Borough into the lead.
And five minutes later, Gosport’s amazing comeback was complete as Claridge hammered a third to seal his side’s promotion.