Peterborough moved to the top of the Sky Bet League One table following a 3-0 win at Plymouth.
Darren Ferguson's Posh extended their winning streak to five games while ending Argyle's nine-match unbeaten league run.
Argyle goalkeeper Michael Cooper saved from Sammie Szmodics after 13 minutes but could only watch as the United forward fired just wide from 20 yards a minute later.
Szmodics blazed over the crossbar after being teed up by Jonson Clarke-Harris just after the half-hour mark as the striker had raced clear from the halfway after tackling Argyle central defender Jerome Opoku.
Argyle's best first-half opportunity fell to hard-working midfielder Panutche Camara.
His chest down and goal-bound angled volley was superbly saved by Christy Pym after 40 minutes.
Peterborough striker Szmodics fired the visitors ahead from close range in the 46th minute as Argyle's defence failed to clear Joe Ward's cross from the right.
Szmodics was also heavily involved in Posh's second goal, converted by the league's top scorer Clarke-Harris after 63 minutes.
His pass from the centre circle out wide on the right to Ward was crossed into the path of on-running Clarke-Harris, who slotted the ball home to score for the sixth successive game.
Peterborough wrapped up the points when Jack Taylor sent a 25-yard strike into the top corner with six minutes remaining.