Mansfield lost their fourth game in a row as a late goal from Ade Adeyemo secured Crawley a well-deserved 1-0 victory.
Despite dominating the second half, it took Crawley until the end to break down Stags' defense.
The first half was messy with limited scoring opportunities. Will Swan, a former Mansfield player, had two shots on goal, but keeper Christy Pym was able to deny both attempts.
Baily Cargill came closest to scoring in the first half when he headed into the side-netting.
Pym made a crucial save in the 55th minute, deflecting a powerful shot from Tyreece John-Jules. He also stopped a low effort from Rushian Hepburn-Murphy in the 67th minute.
Crawley had several chances in quick succession in the second half. Pym made a brilliant save to deny Dion Conroy's shot.
Crawley's persistence paid off in the 81st minute when Adeyemo scored from close range after Pym failed to hold onto Swan's shot.
In stoppage time, Aden Flint nearly equalized for Mansfield with a header, but Charlie Barker made a crucial goal-line clearance.