Marvin Emnes scored a late winner as Middlesbrough sent Sheffield United to the bottom of the Championship table with a 2-1 victory at Bramall Lane.
Matthew Bates fired the visitors ahead from 12 yards but Matthew Lowton headed the Blades level before the break.
Joe Mattock tested Boro stopper Paul Smith with an angled drive while United keeper Steve Simonsen kept out volleys from Scott McDonald and Rhys Williams.
But Simonsen was beaten by a low shot from striker Emnes in the last minute.
The defeat, coupled with Preston picking up a point at Portsmouth and Scunthorpe recording a 4-1 victory over Championship leaders QPR, consigned the Blades to the bottom of the table, seven points from safety.
The Blades conceded in the 18th minute when Bates latched on to Andrew Taylor's cross and fired home but Lowton nodded Bjorn Helge Riise's back-post cross into the net to reward the home side for a spell of concerted pressure.
Both goalkeepers made crucial saves to keep their respective sides in the game with Simonsen hurling himself full length to keep out a Wiliams volley while Smith denied Darius Henderson from close-range.
The Blades had been chasing victory with substitute Marcus Bent guilty of missing a gilt-edged chance from Bjorn Helge Riise's corner on the edge of the six-yard box while Joe Mattock lashed a 20-yard volley wide.
And they were made to pay when Julio Arca picked out Emnes' run through the middle and the Dutchman calmly tucked his shot inside Simonsen's far post to move Boro 11 points clear of the relegation zone.