Mansfield fell to a second consecutive home defeat as fellow promotion hopeful Bradford took all three points from a pulse-pounding encounter that ended 2-1.
After a slow start, City forced a double save from Stags keeper Christy Pym who blocked attempts by Scott Banks and Tyreik Wright.
Two minutes later, the Bantams led when Brad Halliday’s low cross was cleared only to skipper Richie Smallwood, who hit the ball home from 14 yards the first time.
Alex Gilliead almost doubled the lead at the end of halftime, but Pym was able to collect easily.
Halliday curled just wide for City early in the second half, before a fine solo goal from Andy Cook against his former club doubled their lead, slashed in and beat James Perch before drilling low into the corner of the net.
City saw Matty Platt sent off for a second bookable foul. Mansfield quickly narrowed the deficit as Will Swan scored from close range after Elliott Hewitt’s header was parried from a corner.
And despite much late pressure from the hosts, City held on to a hard-earned win.