United chalked up their first away win of the season thanks to goals from strikers David Goodwillie and Jon Daly.
As had been anticipated, like the St Johnstone game, it was another hard shift. Indeed, it was United's more clinical finishing that won the day.
Whilst Kilmarnock edged it on pressure, they had left their shooting boots at home. Goodie's opener after 15 minutes came with an improvised shot on the turn which came off his other foot to rear up and over the keeper.
Other than Conor Sammon going close on a couple of occasion, and Dusan Pernis beating away a da Silva shot, Killie rarely threatened.
Best chance they had of getting back in the game came after 65 minutes when Craig Bryson seemed set to equalise only to drag his shot wide of the post from 12 yards.
And with 19 minutes left, Jon Daly bundled in a second after Scott Severin nodded down a Paul Dixon corner.
Home hopes of salvaging anything suffered a further blow when defender Frazer Wright was sent off with eight minutes left.
United's only disappointment was losing a goal in stoppage time, Craig Bryson's cross being headed down by da Silva for Sammon to at least get some reward for his tireless efforts.
But it was a good win against a much improved Kilmarnock side and completing a satisfactory afternoon, results elsewhere mean Peter Houston's side now sit fourth in the SPL.