It was a comprehensive display from the hosts, who looked a level above Spurs from kick-off and only grew in the game as time went on.
The result - and performance - may be seen as somewhat of a turning point for Erik ten Hag, with three Premier League losses already on the board after 10 games.
Man Utd dominated the first-half and Spurs could've considered themselves lucky to have gone in at the break with their clean sheet still intact.
But just a few minutes into the second-half, a heavily deflected shot by Fred found its way beyond Hugo Lloris to give United a deserved lead.
The goal seemingly dampened Spurs' spirits as they continued to offer very little going forward as United pressed for a second.
Bruno Fernandes bagged his goal; a spectacular effort from the edge of the area that found the top corner of the net beyond Lloris.
The midfielder was denied a brace by the linesman's flag, but in truth 3-0 would have been a tame scoreline for an uninspired Spurs performance at Old Trafford.
With a game-in-hand, United could go one point behind Spurs in third place with a win over Chelsea at the weekend.
