The amazing Mason Greenwood was the highlight as United made it four wins in a row to cement fifth position and close the gap on third and fourth.
Villa, who were game in the first half, drop down a place to second-bottom and look certain to go down.
Villa started the game well, putting United under pressure with a series of crosses before Trezeguet hit the post.
But on 27 minutes, Bruno Fernandes pirouetted on the ball just inside the box and Kourtney Hause was already committed to the challenge; Jon Moss gave a marginal penalty, and Fernandes swept home with ludicrous ease.
United did not improve greatly thereafter, and with half-time looming, Villa forced a couple of corners.
The first almost resulted in a United goal on the counter and the second did, Greenwood punishing home a finish of mortifying, affirming expertise after fine work from Anthony Martial.
When the second half started Villa looked a beaten side, and on 58 minutes went further behind, Paul Pogba curling home from outside the box.
The home side will have feared things getting messy, but Ole Gunnar Solskjaer made changes, United more or less declared and Villa played at walking pace; both sides have plenty of work still to do.