It was only Tottenham's first game of their Premiership campaign, having had their first postponed
due to the London riots.
Despite an action-packed first-half, neither team took advantage of their chances and the game remained goalless at the break.
Determined to make an impression on Sir Alex Ferguson, Welbeck
gave United the lead as he headed in Tom Cleverley's cross in the 61st minute.
United's second came in the 76th minute, when Welbeck concluded some beautiful link-up play with a skillful back-heel, allowing Anderson to tap the ball in from close range.
Wayne Rooney put the icing on the cake just three minutes from time, after heading in Ryan Giggs' cross.
: "The second-half performance was absolutely fantastic. It was a fast game in the first half, it was end-to-end. Tottenham had a lot of possession, but in the second half we just took off."