Alex Mitchell's first City goal helped his side to all three points at Fleetwood Town.
The Cod Army had the first chance of the afternoon in the second minute after they worked it well to Jack Marriott in the centre who sent his snapshot wide of the near post.
It was the Imps who took the lead though in the sixth minute after Lasse Sorensen's long throw from the right was flicked on by Reeco Hackett to Alex Mitchell at the far post who volleyed home from close range.
City restricted the hosts to any clear chances in the 20 minutes that followed this and created one of their own through Ethan Hamilton whose corner to the edge of the box was headed just over by Ted Bishop.
Xavier Simons almost brought his side level midway through the first half after he found space to strike goalwards from the edge of the area, although his effort was easily caught by Lukas Jensen.
Hamilton looked to try his luck in the 38th minute following a neat bit of build-up play, as his 25-yard strike was initially fumbled by Jay Lynch before eventually reclaming the ball.
Fleetwood built some pressure at the start of the second half which saw them create two openings, with Marriott and Junior Quitirna's efforts from just inside the area both being held by Jensen.
Lee Johnson's side then looked to cause a threat from two free-kicks. The first from 20-yards out was blasted against the wall by Quitirna before he sent a wide free-kick towards Bosun Lawal at the back post who couldn't turn it in.
City showed a lot of grit and determination to keep their lead intact heading into the final 10 minutes, as Scott Robertson's slightly deflected shot from the edge of the area the nearest the Cods came.
Toto Nsiala was then shown a straight red in the sixth minute of stoppage time after Jovon Makama was brought down after being put clean through on goal from a long upfield ball from Mitchell.
Tom Shaw's side stood firm in the final minutes to pick up a first ever win at Fleetwood Town.
Fleetwood: Jay Lynch, Carl Johnston (Ryan Broom 75'), Adam Montgomery (Kabongo Tshimanga 46'), Bosun Lawal (Promise Omochere 90+2'), Josh Vela , Danny Mayor, Jack Marriott, Junior Quitirna, Xavier Simons (Scott Robertson 71'), Toto Nsila, Josh Earl. Subs (not used): Stephen McMullan, Brendan Wiredu, Connor Teale.
Imps: Lukas Jensen, Lasse Sorensen, Adam Jackson, Ethan Erhahon, Reeco Hackett (Jovon Makama 49'), Ali Smith, Ted Bishop (Hakeeb Adelakun 81'), Ethan Hamilton, Paudie O'Connor , Jack Burroughs (Sean Roughan 67'), Alex Mitchell. Subs (not used): Jordan Wright, Dylan Duffy, TJ Eyoma, Jack Vale.
Goals: Mitchell (6').
Referee: Tom Reeves.