Goals in the final five minutes from substitutes Armand Gnanduillet and Tendayi Darikwa sent Paul Cook's side top after David Connolly had been dismissed seven minutes before the half-time break for violent conduct.
They leapfrogged Oxford, who drew 1-1 at home with Rochdale.
James Constable gave the hosts the lead midway through the first half but Matthew Lund earned a point for Rochdale with a goal five minutes after the interval.
Rock-bottom Accrington Stanley's woes continued as they faced Burton Albion, who now occupy the third automatic promotion slot after Adam Reed's stoppage-time strike saw them come away from the Crown Ground with a 1-0 win.
AFC Wimbledon's strong start to the season was boosted further with a 2-0 home success over Fleetwood Town.
Harry Pell opened the scoring from the spot in the 42nd minute before Michael Smith's goal on the stroke of half-time sealed the points.
Exeter City sit level with Wimbledon on 10 points from five games after they came from behind to beat York City 2-1 at St James' Park.
Ryan Jarvis put York ahead in the 19th minute but Alan Gow equalised four minutes later and then bagged what proved to be the winner with 18 minutes left.
Southend United sit in the final play-off place, despite going down 2-1 at Wycombe Wanderers.
Dean Morgan put the hosts in front on seven minutes only to see the in-form Freddy Eastwood level the scores in the 14th minute with his third league goal of the season.
However, Steven Craig struck 13 minutes before half time to elevate Wycombe to 12th position.
Hartlepool United remain in the bottom two, but came away from a long trip to Torquay United with a point after a 0-0 draw, while league newcomers Newport County continued their solid start to the season with a 1-1 draw away to Scunthorpe United.
Mansfield Town, promoted alongside Newport last season, enjoyed a fine 3-0 home win over Dagenham and Redbridge and Bury were similarly comfortable, although they had to come from behind to beat Cheltenham Town 4-1 at Gigg Lane.
Andrew Procter put through his own net to give Cheltenham the lead inside five minutes, before Danny Mayor equalised five minutes later.
Procter then redeemed himself with a goal at the right end in the 12th minute, before Nathan Cameron added a third to cap an entertaining opening 17 minutes and substitue Jessy Reindorf put the gloss on the victory 14 minutes from time as Bury climbed to 10th.
Bristol Rovers sit just behind them following a 1-0 win over Northampton Town.
Tom Lockyer's goal in the second minute proved the difference, and Northampton's bad day was compounded when they saw Roy O'Donovan sent off in stoppage time for a second bookable offence.
Morecambe jumped to 13th place after coming from behind to beat Plymouth Argyle 2-1 at home.
Reuben Reid put the visitors ahead from the spot in the 27th minute, but that lead lasted just two minutes as Kevin Ellison levelled the scores.
Padraig Amond then struck the winner six minutes from time to hand Morecambe the points.
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