Gainsborough suffered their first defeat of the season as they fell to a resurgent second half performance from Harrogate.
The Blues lead at half time thanks to a first Trinity goal for Nick Bignall before two goals in four minutes on the hour and a late volley gave the hosts the three points.
It was an even start to the game at the CNG Stadium with both sides exchanging corners.
It was from a corner where the home side had their first effort as Cecil Nyoni turned a shot goal wards from the edge of the box that was cleared firmly by the boot of Jan Budtz.
The game ebbed and flowed for a while until a defensive error from Harrogate left back Andy McWilliams led to the opening goal.
The defender tried to cushion the ball back with his head to Peter Crook in the Town net.
He could not get another power on it and new boy Nick Bignll picked his pocket and slotted the ball through the keepers legs.
Minutes later and the Blues almost extended their lead.
Bignall once more was involved down the right and a clipped cross from the former Reading man was headed wide by a diving Nathan Jarman.
The first few minutes of the second term saw a couple of quick chances for the Blues.
A battling Jarman forced his way to the byeline, got in a cross and a defender miscued the clearance and cleared the bar by a matter of inches.
From the corner Jake Picton tested goalkeeper Crook with a header.
Trinity were issued a warning shot when Town hit the post and in the 60th minute, Harrogate equalised.
A deflected Colbeck cross fell perfectly onto the head of ex Blue Dominic Knowles and he duly dispatched it.
Four minute later and the home side completed the turnaround.
The goal owed a lot to fortune once more as substitute Brendan Daniels turned in the box, got away a shot which was deflected and went in via the post.
Harrogate continued to press and in the last minute, Daniels grabbed a second off the bench with a crisp volley from the edge of the box.
Gainsborough Trinity: Budtz, Roma, Lacey, Wilson, Quinn, Picton, Russell (Rigby 68), D’Laryea, Bignall, Jarman, Yates (Stamp 75). Subs: Binns, Karkach, Davis.
Harrogate Town: Crook, Turner, McWilliams, Thirlwell, Shiels, Ellis, Colbeck (Thewlis 77), Nyoni, Clayton, Knowles, Swain (Daniels 57). Subs: Kerry, Bloomer, Emmett.
Goal scorers: Bignall 20; Knowles 60, Daniels 64, 89.
Referee: Mr G Fyvie. Assistants: Mr D Watson, Mr J Goodwin.