Darren Ferguson's men produced an impressive performance to record their fourth win in five league matches, with goals from Conor Washington, Kgosietsile Ntlhe – who was later sent off – and Jermaine Anderson ensuring maximum points.
The win saw Peterborough leapfrog Fleetwood Town into top spot, although Stephen Dobbie's 83rd-minute strike salvaged a point for Graham Alexander's side as they drew 1-1 with Leyton Orient.
Chesterfield's 2-1 success at Port Vale was marred by accusations of racist abuse.
The visitors held on with 10 men following Ian Evatt's late dismissal, but striker Armand Gnanduillet was allegedly targeted with racial slurs from the home section as he left the field at Vale Park.
"There were problems with racism after the game, it has been documented by the stewards and everyone else. That is not for me to comment on now because it is a serious issue," said Chesterfield boss Paul Cook.
Milton Keynes Dons were another team to overcome a dismissal as they built on their stunning 4-0 League Cup win over Manchester United on Tuesday by beating Crawley Town 2-0 in spite of Kyle McFadzean's red card.
Crewe Alexandra are still waiting for their first points following a 2-0 loss to Gillingham, but Scunthorpe United sealed their maiden victory this term by overcoming fellow early strugglers Walsall 2-1.
Bradford City carried the momentum from their midweek League Cup heroics against Leeds United into the league with a 2-0 triumph at Rochdale, while Preston North End continued their unbeaten start to the league campaign with a 1-1 draw against Sheffield United.
Elsewhere, Oldham Athletic claimed a 2-0 victory at Doncaster Rovers, Barnsley were held to a 1-1 draw by Yeovil Town and Swindon Town played out a 1-1 stalemate with Coventry City.