Cheltenham overcame the 18th-minute dismissal of midfielder Kyle Storer to hold in-form Mansfield to a 0-0 draw at Whaddon Road.The flashpoint arrived when Storer launched into Jamie McGuire with a full-blooded challenge on the halfway line in front of the visiting bench.Referee Charles Breakspear wasted little time in brandishing a straight red card, with Robins manager Gary Johnson sent from the dugout in the aftermath.Cheltenham were rocked for a spell but the Stags, beaten once in their previous 12 Sky Bet League Two outings, could not find a way through as Ben Whiteman scuffed horribly off target from two presentable openings.The hosts began the second half on the front foot with Mansfield skipper Lee Collins getting a vital touch on Will Boyle's on-target header shortly before Liam Davis hit the crossbar straight from a corner on 51 minutes.Whiteman miscued again from 18 yards just before the hour and Mansfield substitute Shaquile Coulthirst lifted over from inside the box late on as Cheltenham secured a fourth successive clean sheet.