The game that started very scrappy with both sides not taking a risk in a vital match.
On 11 minutes Gareth Jelleyman almost headed into his own net after a good run by Rushden striker Chris O'Grady.
Mansfield went ahead in the 18th minute when Jake Buxton crossed from the right to find the unmarked Simon Brown, who headed powerfully past Jamie Young.
Rushden found it hard to create clear cut chances and looked a side who are desperately short on goals.
On 32 minutes Mansfield should have gone further ahead when Gus Uhlenbeek crossed from the right after Jonathon D'Lareya missed his shot and Adam Rundle blazed his follow up well over.
On 47 minutes substitute Allan Russell crossed from the right and Adam Rundle was inches wide from the header.
Mansfield went further ahead in the 50th minute when Giles Coke superbly beat several Rushden defenders before coolly shooting past Young.
Rusden pulled a goal back in the 56th minute when John Dempster headed home David Bell's corner from ten yards out.
Rushden took confidence from the goal and began to dictate the game and press forward for an equaliser, although on 68 minutes Buxton went up for Mansfield, but his header was inches wide.
Veteran keeper Kevin Pressman was forced to make several good saves to keep Rushden at bay saving from Bell in the 70th minute.
On 76 minutes a fine Rushden move between Dave Savage and Lee Tomlin ended with Marcus Kelly blasting well over.
On 81 minutes Young was forced to save at the feet of Richard Barker following another good cross from Buxton, but Mansfield held on for the victory despite Rushden's frantic attempts to gain an equaliser.