SLIDESHOW: Mansfield Town v Oxford United action picture slideshow
The visitors were already ahead when Jamie McGuire was shown the Stags’ sixth red card of the season so far on 23 minutes.
Lee Stevenson did level for the 10 men in the eight minutes of first half stoppage time but, even deeper into it, James Constable came on as sub to restore Oxford’s lead, and they sealed victory with a killer third midway through the second half.
Stags now prepare to head to high-flying Fleetwood Town this Saturday.
Slideshow pictures by Richard Parkes.