Neil Warnock's Blades showed their mettle as they pulled off an unlikely win against top of the table Crystal Palace at Selhurst Park.
In a thrilling all-action encounter Sheffield United had keeper Paddy Kenny carried off, conceded two penalties and saw red with midfielder Michael Brown being sent off.
But against all the odds the Yorkshiremen showed their character and resilience to earn a deserved three points thanks to first-half goals from Peter Ndlovu and Wayne Allison.
It all started on 18 minutes with Ndlovu firing the Blades in front after Shaun Derry had lost out in midfield.
In the 26th minute Dougie Freedman's mazy run came to an abrupt end after being floored by Phil Jagielka, but with Freedman unable to take any further part, Neil Shipperley fluffed the spot-kick with Kenny making an easy stop to his right.
Seventeen minutes later Kenny was carried off after colliding with Derry and the injury caused six minutes of injury time to be added before Kenny was stretchered off.
Jagielka took over in goal and United got some relief as Allison doubled the Blades' lead with a far-post header from Michael Tonge's cross from the left.
Michael Brown got his marching orders midway through the second half following a bad tackle on Wayne Routledge and nine minutes later the Eagles had hope as Andrew Johnson successfully converted from the penalty spot after being tripped by Tonge.
Palace threw the kitchen sink at United, but the Blades held out superbly for a remarkable three points.