Bristol City moved 10 points clear of the chasing pack as they were the only side in the top five to win in League One this evening.
The Robins went down early on as Chris Dagnall put Leyton Orient ahead, but goals from Luke Freeman and Aden Flint before half time put the league leaders in charge before Aaron Wilbraham's 13th goal of the season wrapped up the win.
Matt Done continued his fine form for the Blades since joining from Rochdale when he put his side ahead just after the hour mark, only for Jack Payne and Conor Washington to strike in the dying minutes to nick the win.
It was a similar story at Deepdale where Doncaster Rovers came from a goal behind to lead Preston North End 2-1 thanks to late efforts from Harry Forrester and Curtis Main, until Jermain Beckford's late goal salvaged a draw for Preston who move into second.
Bradford City closed the gap on a playoff place to one point as Francois Zoko's first goal for the club earned a 1-0 win over Crawley Town, while Barnsley also move up the table as George Waring's strike 10 minutes into the second half at Oakwell ensured that Tony Mowbray got off to a losing start as Coventry City boss.
At the bottom, Notts County moved away from trouble as Paddy McCourt's effort gave the Magpies a 1-0 away win over relegation rivals Colchester United, while Yeovil Town remain rooted to the bottom of the table after Jordy Hiwula's goal was enough to give Walsall all three points at Huish Park.
It was a high-scoring affair at Highbury Stadium too, as a George Evans strike 17 minutes from time meant Scunthorpe United earned a precious 2-2 draw with Fleetwood Town, while Oldham Athletic ended their losing streak with a 1-0 win over Port Vale.
Results in full: Sheffield United 1-2 Peterborough United, Barnsley 1-0 Coventry City, Bradford City 1-0 Crawley Town, Colchester United 0-1 Notts County, Fleetwood Town 2-2 Scunthorpe United, Leyton Orient 1-3 Bristol City, MK Dons 1-2 Chesterfield, Port Vale 0-1 Oldham Athletic, Preston North End 2-2 Doncaster Rovers, Rochdale 4-0 Crewe Alexandra, Swindon Town 0-3 Gillingham, Yeovil Town 0-1 Walsall