In form Boston's six-match unbeaten run came to an end as two Junior Mendes goals in 18 minutes clinched promotion-chasing Mansfield's second home win in a week.
United, minus the sick leading scorer Neil Redfearn, had deservedly taken the lead after edging a poor a first half.
But after Mendes headed in his 5th goal of the season to equalise - the first goal Boston had conceded in 258 minutes, the Stags were always in charge.
Mansfield had created the first chance with a flowing crossfield move involving Wayne Corden, Neil Mackenzie and Liam Lawrence. From Lawrence's perfect lay-off Bobby Hassell almost marked his returned from a seven-match injury lay-off with a goal, but his low drive was blocked by the first of several fine Paul Bastock saves.
Boston took the lead in 26th minute with their first shot of the match. Simon Rusk's right-wing cross was helped on by Mansfield defender Dave Artell and the unmarked Simon Weatherstone hammered home.
Within six minutes the home side were level. Liam Lawrence slide-rule pass released Mendes and he raced clear of two defenders before firing into the bottom corner from a tight angle.
Mendes, who went close with a carbon copy second a minute later, completed Mansfield's fight back six minutes into the second half when he headed in a pin-point Lawrence cross.
The game then exploded into life with the Stags creating a glut of chances in quick succession. With Boston reeling Colin Larkin was thwarted by Bastock's finger-tip save and then Mendes was denied a hat-trick by Chris Hogg's goal-line clearance.
Tony Vaughan's fierce header from a Corden corner was then beaten away on the line by the over-worked keeper.
Boston almost made Mansfield pay for wasting those chances in a nervy finish.
Stuart Balmer's low drive was held by the diving Kevin Pilkington, Weatherstone's free header looped over the bar and then three minutes into injury time Lee Beavers' fierce drive was blocked for a corner.