Scunthorpe threw themselves a relegation lifeline and dragged Crystal Palace right back into trouble at the foot of the npower Championship with a 2-1 win.
Goals in each half from David Mirfin and Ramon Nunez settled a real six-pointer at Selhurst as United closed the gap on the fourth-bottom Eagles to just three.
Palace had not lost at home since October, some 18 matches ago, while the Iron were on the verge of a club record 10th straight defeat on the road.
So the form book was well and truly ripped to pieces when centre-half Mirfin popped up with his third goal of the season and Honduran Nunez hit his first in English football.
Sean Scannell pulled one back for Palace but Dougie Freedman's side, who would have been nine points clear of the drop zone with a victory, now face a nervous end to the season.
Both sides finished with 10 men, Joe Garner shown a second yellow card for a foul on Wilfried Zaha and Scannell following him for lunging at Andy Hughes as the pressure of the relegation battle began to show.