Oxford closed to within six points of a Sky Bet League One play-off place courtesy of a 2-1 success at Peterborough - and all but ended their hosts' top-six hopes in the process.Michael Appleton's men hit the front on 23 minutes at the ABAX Stadium when Phil Edwards headed in a Rob Hall corner.And they doubled their advantage when Conor McAleny tucked away a slick Chris Maguire pass with 19 minutes to go.The goalscorer was fortunate to still be on the pitch after escaping with a yellow card from referee Mark Heywood when throwing Jack Baldwin to the floor in first-half stoppage time.It was a success which featured a series of fine saves from Oxford goalkeeper Simon Eastwood, whose classiest contribution was keeping out an early Leo Da Silva Lopes effort.Eastwood also denied Chris Forrester and Craig Mackail-Smith early in the second period as Posh chased a leveller.Even when he was beaten, Andrew Hughes headed against the crossbar before Posh saw Da Silva Lopes dismissed late on for collecting a second caution.They did net in stoppage time as Mackail-Smith hit his 100th goal for the club, but it was not enough.