In addition to Chesterfield and Oxford, Burton Albion remain unbeaten in the league. Adam Reed's 98th-minute strike sealed a 1-0 win for the Brewers at Accrington Stanley, who remain winless and rock bottom.
Hartlepool United are the only other side who are yet to win this season. However, the Monkey Hangers did manage to double their points tally by recording a goalless draw at Torquay United.
Results in full: AFC Wimbledon 2-0 Fleetwood Town, Accrington Stanley 0-1 Burton Albion, Bristol Rovers 1-0 Northampton Town, Bury 4-1 Cheltenham Town, Exeter City 2-1 York City, Mansfield Town 3-0 Dagenham & Redbridge, Morecambe 2-1 Plymouth Argyle, Oxford United 1-1 Rochdale, Portsmouth 0-2 Chesterfield, Scunthorpe United 1-1 Newport County, Torquay United 0-0 Hartlepool United, Wycombe Wanderers 2-1 Southend United.