Ellis Harrison struck in the second half to secure Bristol Rovers a 1-0 win at relegation-threatened MK Dons as the Pirates moved within four points of the play-off places.The forward's 12th league goal of the season condemned struggling MK to their 10th-straight league game without a win but it was Rovers' third win in five as they look to chase down sixth-placed Plymouth.The hosts started brightly and went close to taking the lead when Robbie Muirhead cut inside on 15 minutes, before firing a left-footed strike just over the Rovers goal.Liam Sercombe threatened for the visitors 10 minutes later when his half-volley inside the Dons box was superbly saved by Lee Nicholls.Darrell Clarke's Pirates then took a deserved lead five minutes after the break as Harrison broke down the flank before cutting inside and delicately dinking a fine finish over the head of MK keeper Nicholls.And despite Muirhead forcing Rovers stopper Sam Slocombe into a testing save late on, Dan Micciche's men couldn't find a leveller as relegation to League Two becomes increasingly likely.