Kenny Pogue scored twice as Sevenoaks Town suffered their second home defeat of the season.
Pogue struck early and late against his old club to send the teams in level at the break.
He put them in front after only four minutes, before Hastings hit back scoring twice in three minutes late in the first half, only for Pogue to get his second in stoppage-time.
The game turned in the space of sixty seconds 13 minutes from time - Hastings goalkeeper Charlie Horlock made a double stop to keep out close-range efforts from Pogue and skipper Rob Saunders, play switching immediately to the other end, as two-goal Daniel Ajakaiye hit the winner.
Pogue suffered a recurrence late on, being replaced by Osman Proni.
Town rallied well, debutant Alec Fiddis saw his effort pushed away by Horlock, then Sam Crabb and Frankie Sawyer had efforts blocked in a vain late attempt to snatch a point.
Town drafted in Dartford goalkeeper Ryan Nicholls to replace injured Ben Bridle-Card, returning for a second stint as cover, against another of his old clubs.
Nicholls made two good saves, including pushing one effort off a post for a corner, before Hastings turned things around.
He tried hard to close down Ajakaiye, but the Hastings striker still found room to squeeze the ball home from a tight angle for the equaliser, but had no chance for the second as unmarked ex Darts youngster Dajonne Golding pounced at the far post.
Referee Ian Fissenden added two minutes stoppage-time at the end of the first half - still time for Town to level with their best move of the match.
Crabb put Sawyer away down the right, and his perfect low cross picked out Pogue at the far post.
Nicholls did well again in the second half, stopping one effort with his foot, and then tipping another effort over the bar.
Town lost midfielder Mikey Dalton at half-time with a foot injury, Andreas Toban replaced him.