Adam Murray scored the winner against his former club with just two minutes to go to earn Mansfield a 2-1 victory at home to Oxford.
It had looked like the points would be shared after Danny Hylton had levelled from the spot for Oxford with 12 minutes remaining.
But Murray, who had been on the pitch for just three minutes, latched on to a loose ball before drilling a fierce effort from 16 yards low past George Long.
Mansfield had taken the lead in the 39th minute when defender Ryan Tafazolli fired into an empty net after Chris Clements' free-kick had hit the post.
The commanding defender nearly doubled the home side's advantage in first-half stoppage time when he headed Clements' free-kick just wide.
The visitors were then given an unlikely lifeline in the 78th minute when Tafazolli brought down substitute Hylton.
Hylton then stepped up to confidently bury the ball past Sascha Studer into the bottom-right corner with a firmly hit strike.
But Murray struck at the death to earn Stags their first win of the campaign.