Morecambe, meanwhile, celebrated achieving their pre-season safety target of 50 points.
The Stags rallied bravely in the second half after an awful first 45 minutes when they gifted the visitors two goals and could have trailed by more.
But their poor record this season of never recovering to win a game after going behind continued as they celebrated manager Billy Dearden's birthday - he was 64 on Monday - in the worst possible way.
The visitors should have grabbed a second minute lead when Carl Baker's right-wing cross picked out the unmarked Wayne Curtis, but he mis-controlled the ball and John Mullins scrambled clear.
However, they made no mistake moments later when Baker again crossed and Jim Bentley rose above Mullins at the far post to head firmly into the roof of the net.
The Stags looked vulnerable from set-pieces and, from a Garry Thompson corner, former Stags defender Dave Artell rifled over from 10 yards as the Shrimps threatened to double their lead.
Morecambe, quick on the break and out muscling the home side, forced several corners in the opening quarter, but from one flag-kick for the home side Micky Boulding might have levelled but his glancing header was easy for keeper Shwan Jalal.
But the visitors did double their lead deservedly in the 24th minute.
Again the Stags failed to clear a cross and this time Matthew Blinkhorn was left completely unmarked to easily head past the stranded Carl Muggleton from a curling Craig Stanley cross.
Within a minute the Stags squandered a rare lifeline when Jefferson Louis looped a tame header from a Mullins cross into the arms of the keeper.
Then the big striker skidded a low shot narrowly wide on his full home debut.
Three minutes into the second half the Stags, who were clearly lifted by a half-time rocket from Dearden, did grab the lifeline.
A corner was cleared to Lee Bell and he hammered a 20-yard volley into the top corner.
Moments later, Boulding curled a 25-yard effort inches past the post with Jalal beaten.
Then Stephen Dawson weaved his way to the byline, but his pull back just failed to pick out the lurking Boulding.
Louis fired narrowly wide as the Stags pressed for an equaliser, while at the other end Bentley curled a header narrowly wide and substitute Henry McStay nodded wide of an empty net as Morecambe looked to secure victory.
But Morecambe hung on despite substitute Ian Holmes poking wide when well placed deep into injury time for the home side to record the double over relegation haunted Mansfield.