SUNDERLAND'S first win at Old Trafford in 46 years has put Gustavo Poyet's men on the brink of winning the relegation battle which has plagued them all season.
Seb Larsson's brilliant volley inside 30 minutes proved the deciding factor on an afternoon when his goal helped condemn both Cardiff City and Fulham to next season in the Championship.
Now Sunderland, who have a far superior goal difference than those below them, will effectively be guaranteed Premier League status tomorrow if Norwich City lose at Chelsea.
Sunderland could not have wished for a better run of form at this stage of the season, collecting ten points from a possible 12 during a run which has seen them face United, Chelsea, Manchester City as well as Cardiff.
And it will take the pressure off Poyet's team as they head in to back-to-back home games with West Brom on Wednesday and then Swansea next Sunday regardless of the outcome at Stamford Bridge tomorrow.
Sunderland held on to Larsson's winner with some strong defending and inflicted a first defeat on Manchester United's caretaker manager Ryan Giggs by securing a first victory at Old Trafford since 1968.
Sunderland were effective across the pitch in the first half. They regularly closed down the Manchester United shirts and when the home side did threaten they could find no way through the banks of yellow shirts.
Goalkeeper Vito Mannone only had a couple of real saves to make in the first half. The first was to gather a tame header from Patrice Evra and the second, right on half-time, was a comfortable low stop to his left when Juan Mata struck from 20 yards.
By the time Mata had tried his luck with that effort, Sunderland had already gone ahead on half hour. It was sweet goal too.
After retaining possession down the left, Sunderland ended up working the ball to Connor Wickham.
The revitalised striker held off his marker before picking out the lurking Larsson standing just inside the area unmarked. The Swede applied a cushioned right foot volley which rolled inside David De Gea's far post.
Giggs even introduced Robin Van Persie and Danny Welbeck during the second half in a bid to turn things around. The former almost scored at Mannone's near post too with 16 minutes remaining.
Before that Sunderland substitute Emanuele Giaccherini came within inches of extending the lead at the other end. The Italian found the foot of the post after Jozy Altidore had crossed from the right.
Manchester United kept pressing in the closing stages and Javier Hernandez wasted a glorious chance when he blazed over from 12 yards following Evra's cut back.
Sunderland still actually created chances and Borini was unfortunate to see a fine shot curl towards goal and bounce to safety off the crossbar.
Sunderland, though, had already done enough to pretty much preserve their place in the top-flight - and the celebrations began.