Lincoln fell one day short of completing a year unbeaten in all competitions at Sincil Bank as Danny Rose came off the bench to head Mansfield to a 1-0 victory.
It took Rose just three minutes to find the net as he nodded home Hayden White's cross from the right - the Stags' first effort on goal.
A series of blocks by Mansfield defender David Mirfin kept the scores level at the break with the defender twice denying Michael Bostwick and Billy Knott clear goalscoring opportunities.
At the other end, Alex MacDonald went close with a clever free-kick midway through the first half that deceived the Lincoln wall and goalkeeper Paul Farman.
Mansfield boss Steve Evans introduced Rose just before the hour, much to the delight of the travelling 1,459 supporters, and it was a move that immediately paid dividends.
A marauding run from full-back White resulted in a pinpoint cross to the head of Rose and the substitute made no mistake.
Another sub, Lincoln's Sean Long, almost picked out Knott for an equaliser 10 minutes from time, but the midfielder just failed to connect with his cross.