The United winger scored a brace and team-mate Lawrence Shankland went one better, netting a hat-trick as David Hopkin’s side were hammered.
Youngster Logan Chalmers also chipped in with a goal to keep United top of the Championship on goal difference.
Shankland took his tally for the season so far to 15 but McMullan’s magic was just as important for Robbie Neilson’s promotion hopefuls. The 23-year-old reckons opposition sides will no be shaking in their boots at the prospect of a visit to their home ground where they’ve bagged 18 goals already in their push for promotion.
“That’s four wins our of four at home in the league,” said McMullan.
“Home form is vital when you’re going for a title. We need teams to fear coming here and that’s twice we’ve scored six goals.
“This is a difficult place for teams to come and we want to make it like that for the rest of the season. It was six but it could possibly have been more.”
United made four changes from the side which struggled past Arbroath 2-1 in injury-time a week earlier, with Adrian Sporle, Paul McMullan, Paul Watson and Troy Brown all being given the nod.
Unlike the previous Saturday, the hosts made a whirlwind start inside the first minute.
Watson released winger McMullan down the right and his cross and Shankland executed a low shot into the corner of the net past Danny Rogers from 12 yards.
Three minutes later, Shankland struck again. McMullan sent Peter Pawlett wide on the left and his cross was bundled into the net by the fans’ favourite from close-range.
Then, in 40 minutes, McMullan killed the contest. Liam Smith swept a raking pass over the head of the Ton defence. McMullan was on to it in a flash and wasted no time in sweeping a low shot across Rogers from 12 yards.
United didn’t have to wait too much longer before Shankland completed his hat-trick in 56 minutes, going on a solo run and seeing shot take a slight deflection off Stephen Welsh before nestling in the far corner.
The striker was hungry still for more but it was McMullan who grabbed the next in 79 minutes as he drove into the box before planting a low shot past helpless Rogers.
With six minutes left, substitute Chalmers completed the rout by heading home from McMullan’s inch-perfect cross.
“Lawrence will get all the plaudits but there was nobody that didn’t get pass marks,” said United manager Neilson.