Sir Alex Ferguson's side ground down a dogged Rovers side over the course of an attritional 90 minutes fraught with occasional scares, but ultimately settled by another decisive contribution from Valencia.
The Ecuadorian winger, United's most menacing outlet all evening, blasted home a stunning opener with nine minutes remaining, then teed up substitute Young to crash in a similarly eye-catching clincher five minutes later to move the Reds five points clear of second-placed Manchester City.
While Valencia's display was the outstanding individual contribution, it took a collective heave from United to secure victory, from the last-gasp heroics of David De Gea and his defence to the tireless running of Wayne Rooney, through the limitless patience of the ever-probing Paul Scholes and Michael Carrick.
Sir Alex approached the game with the deployment of three central midfielders, giving Phil Jones his first start at Ewood Park since his transfer to Old Trafford, alongside Paul Scholes and Michael Carrick in midfield. Wayne Rooney and Valencia operated on the left and right flanks respectively, leaving Chicharito as the spearhead of the United attack.
The Mexican had the game's first opening inside five minutes, as Grant Hanley failed to deal with Rooney's flighted diagonal ball. Under pressure from Martin Olsson, however, Chicharito could only scuff his left-footed volley wide, and the striker's frustration grew soon afterwards.