An 84th minute strike from David Beckham sealed all three points for Manchester United at the Riverside Stadium.
United went ahead after just four minutes thanks to an unstoppable drive from England defender Phil Neville.
The United full-back ventured down the left, unchallenged and let fly with a wonderful strike which gave keeper Mark Schwarzer no chance.
Boro fought back in the second half and a packed Riverside Stadium was sent into raptures when defender Ugo Ehiogu put the ball in the back of the net following Jason Gavin's dipping effort.
However, celebrations were short-lived as the £8million record signing from Aston Villa was adjudged to be in an offside position when Irishman Gavin had struck the ball.
The introduction of Argentine whiz-kid Carlos Marinelli added an extra edge to Boro but any hopes the home fans had of an equaliser were dashed when Beckham wrapped things up with a low shot six minutes from time.
After today's other results at the foot of the Premiership, Middlesbrough need just two points from their remaining two games to assure Premiership football next season.
Read more about Middlesbrough FC here.
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