Chris Wilder's men bounced back from a 1-0 defeat in their last league match against Bristol Rovers in fine style, getting off to the perfect start as Sean Rigg put them ahead after 12 minutes with a close-range shot.
They were handed an added boost when Jamie McGuire was shown a straight red card in the 22nd minute, although the hosts made light of their numerical disadvantage to equalise through Lee Stevenson against the run of play in first-half stoppage time.
Striker James Constable ensured they were level for just three minutes though, before Ryan Williams also got on the scoresheet in the 66th minute to secure the convincing win.
However, their impressive form was matched by both Chesterfield and Rochdale, who both clinched victories away from home over Torquay United and Morecambe to move level on points with the new leaders.
Scott Hogan's 68th-minute strike and an own goal from Mark Hughes gave Rochdale the points, although they were denied a clean sheet in the 89th minute by Padraig Amond as it ended 2-1, while Chesterfield defended their 2-0 first-half lead which came via from goals from Oliver Banks and Jay O'Shea.
Former leaders Fleetwood came unstuck, as Luke Norris' injury-time free kick earned rock-bottom Northampton Town just their third league win of the season.
Southend United and Dagenham and Redbridge, meanwhile, moved into the play-off places by beating Exeter City and Burton Albion 2-0 respectively.
At the bottom, Accrington Stanley clinched their second straight win on the road after overcoming Scunthorpe United 2-0 while fellow strugglers Bristol Rovers and Bury took a point apiece from their 1-1 draw, after Danny Hylton cancelled out John-Joe O'Toole's early penalty, while York City also sealed a 1-1 draw against Plymouth Argyle.
Portsmouth and Wycombe Wanderers had little cause for cheer, with a 67th-minute own goal from Billy Knott consigning the latter to a 2-1 loss to Cheltenham, while Guy Whittingham's men fell to their first league defeat since September as an Andy Frampton brace was followed up by goals from Sammy Moore and Michael Smith to seal AFC Wimbledon's impressive 4-0 victory.
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