United's title bid suffered a blip at The Hawthorns as the Reserves failed to score for a second successive game.
Nicky Shorey's first-half opener proved decisive and, despite an improved display after the break, the Reds were unable to find a way past home keeper Luke Daniels. After Jesse Lingard had a couple of early efforts off target, Albion took the lead when a quickly-taken corner allowed Shorey to cut inside and bury a right-footed curler past Ben Amos.
Only a top-class save by Amos prevented Adil Nabi from extending the lead soon afterwards and Albion were decent value for their first-half lead. Wesley Atkinson screwed a shot wide for the hosts while Daniels didn't have to make a save until the 34th minute when he stopped a tame Lingard effort.
Will Keane was constantly outnumbered by defenders in attack but, after Ezekiel Fryers popped a drive the wrong side of the far post, the England Under-21 international muscled his way through to round Daniels, only to see Cameron Gayle make a goalline clearance.
Warren Joyce's half-time team-talk had the desired effect as, with Lingard moving more central, the pressure was applied right from the referee's whistle. Lingard forced a fine save out of Daniels following good work from Will Keane and then pulled the ball agonisingly across the six-yard box with no team-mate on hand to apply the finishing touch.
A brilliant solo run by Will Keane was not matched by the shot, as Daniels saved comfortably, but the home keeper had to be at his best to beat out a Davide Petrucci shot from close range.
Joyce handed teenagers James Wilson and Mats Daehli their debuts at this level and, although