Substitute Kane Hemmings snatched a late winner as Oxford made it five victories in a row in all competitions with a 1-0 success over MK Dons.Hemmings glanced in a header from Rob Hall's right-wing cross to end Dons' own recent good run of six league games unbeaten.A hard-fought encounter at the Kassam Stadium looked to be going the same way as the meeting earlier in the season, which finished in a goalless stalemate.But Hemmings, who had only come on in the 73rd minute, showed his prowess in the box with his 14th goal of the season with just two minutes to go.And Oxford almost made it 2-0 in the sixth minute of stoppage time when Rob Hall was brought down by Darren Potter, who was sent off for his second yellow card, only for Chris Maguire to see his penalty saved by David Martin.Dons had started strongly and only a smart one-handed save down to his left by Simon Eastwood denied Chuks Aneke from 12 yards on three minutes.Stuart O'Keefe should have done better than scoop his shot from six yards over the bar as the visitors squandered another good opportunity and they were made to pay as Hemmings secured a late win.