Phil Edwards claimed a stoppage-time winner as Oxford came from behind to beat promotion-chasing Scunthorpe 2-1 in Sky Bet League One.Paddy Madden curled in a right-footed shot from 14 yards to give the Iron a 12th-minute lead.The rest of the first half was a scrappy affair on a bobbly pitch where getting the ball under control was not easy.The second half was much livelier and captain John Lundstram brought the home side level with a driven half-volley from Joe Skarz's left-wing cross in the 52nd minute.It was Lundstram's first goal of the season and the ex-Everton midfielder was unlucky not to get a second four minutes later with a 20-yard shot which came back off the underside of the crossbar.Madden was always a threat for Scunthorpe, and goalkeeper Simon Eastwood had to beat out a drive from the dangerous striker, and then saved his header a few moments later.Luke Daniels' superb point-blank save kept out Liam Sercombe's volley two minutes from time, but Scunthorpe's defence was under severe pressure and, following a corner, Curtis Nelson drove a low 14-yard shot across goal for Edwards to touch home.