A last-minute winner by Chelsea's Mark Stein sent down the Bramall Lane side. The Blades were twice ahead but Stein was keen to convince his manager, Glenn Hoddle, that he is fit to play in next week's FA Cup Final after missing 14 matches. His two goals in a 3-2 win did more than that.
'If you play Russian Roulette sometimes you are going to get the bullet,' the United manager Dave Bassett said. 'Our season went up in smoke in that one moment.'
After three years at the game's top level, Oldham Athletic finally succumbed. Norwich applied the coup de grace when Robert Ullathorne equalised Sean McCarthy's first-half goal.
Despite taking only four points from the last 33, Ipswich avoided the drop with a gutsy goalless draw at Blackburn. Southampton also drew, 3-3 at West Ham. Saints' saviour, the blessed Matthew Le Tissier, scored two.
In The Second Division, Port Vale's 3-1 win at Brighton won them automatic promotion with Reading despite Plymouth's valiant effort - they won 8-1 at Hartlepool. Argyle are in the play-offs with Stockport, York and Burnley. Blackpool's 4-1 defeat of Leyton Orient and Fulham's 2-1 reverse at Swansea means Jimmy Hill's club are relegated to the bottom division for the first time in their history.
In the Third, Crewe's 2-1 win at promoted Chester, meant they too go up along with champions Shrewsbury. Carlisle's late surge swept them into the play-offs as the form team. They join Wycombe, Preston and Torquay. Northampton, beaten 4-0 at Chesterfield, finish bottom of the whole pile but will not lose league status. The GM Vauxhall Conference champions, Kidderminster, failed to finish ground improvements by the 31 December deadline.
In Scotland, Rangers were beaten 1-0 by relegation-haunted Kilmarnock but still won the Championship because Motherwell could only draw at Raith, who are already down.