Half-time substitute Reggie Lambe struck the winner seven minutes into the second half to clinch Mansfield’s first win in seven matches and their first at One Call Stadium since mid-November.
Lambe pounced in the six-yard area as the excellent Matt Rhead headed Lee Beevers’ deep cross back across the face of goal.
In a scrappy match of few chances on a surface not conducive to quick-passing football, the Stags adapted well.
They lined up for a battle of attrition and that is what they got after manager Adam Murray made six changes – one enforced just before kick-off when Ravenhill picked up a hamstring injury.
Murray dropped wingmen Junior Brown and Lambe and opted for a 3-4-3 formation.
From the kick-off the Stags swept forward and Rhead’s shot was saved in the opening minute. Keeper Day dived to keep out headers from Vadaine Oliver and Michael Raynes.
But the chances were rare and after Lambe’s strike the Stags defended in depth. Their plan worked as Stevenage, beaten for the third successive match to dent their play-off hopes, failed to test Mansfield keeper Lenny Pidgeley on his home debut.