Andy Campbell gave The Bluebirds a 1-0 half-time lead before Robert Earnshaw (pictured) made it two with his first of the season six minutes before the end.
Lee Duxbury got one back for The Latics in the last minute but Lennie Lawrence's men held on for their first three points of the season.
Fellow contenders Wigan Athletic got goals from Andy Liddell and Lee McCulloch in the first half to see off Division Two newcomers Cheltenham Town 2-0 at Whaddon Road.
Tranmere Rovers scored the biggest result of the day with a 4-1 win at Port Vale, despite going behind to a Stephen Brooker goal mid-way through the first half.
However, two goals by Simon Haworth and one each from Jason Koumas and Graham Allen saw off The Valiants and gave the Prenton Park side something to smile about after a difficult pre-season campaign.
New boys Mansfield Town held on for a 4-3 win at home to last season's Division Three champions Plymouth Argyle.
Two goals from Andy White with singles from Craig Disley and Colin Larkin were enough, despite The Pilgrims getting replies from Micky Evans, David Friio and Nathan Lowndes to make the final moments at the Field Mill ground quite tense.
QPR came from a goal down to beat Chesterfield 3-1 at Loftus Road, having gone behind to a Marcus Ebdon penalty early in the second half.
However, goals by Paul Furlong, Richard Langley, and Kevin Gallen gave Rangers the points on the day.
Swindon Town also came from behind to beat Barnsley 3-1 at the County Ground after The Robins went behind through a Chris Lumsdon penalty in the first half.
But a hat-trick from Sam Parkin gave the Wiltshire club an impressive opening victory over one of the three relegated sides from last season.
Bristol City got second half goals from Lee Peacock and Scott Murray to beat Blackpool 2-0 at Ashton Gate, after The Seasiders had Martin Bullock and Lee Collins both sent off after the break.
Barry Fry's Peterborough United held on for a 3-2 victory at Luton Town with goals from Francis Green and two from Andy Clarke.
The Hatters did get goals from Dean Crowe and Ahmet Brkovic but it was not enough to turn things around at Kenilworth Road.
Brentford secured a good 2-0 win at Huddersfield Town with goals by debutants Jamie Fullarton and Rowan Vine at the McAlpine Stadium.
A goal by Thomas Pinault gave Colchester United a 1-0 win against Stockport County at Layer Road with Carlton Palmer's side having to finish the match with ten men after Fraser McLachlan was sent off for two bookable offences.
Northampton Town held Crewe Alexandra to a 1-1 draw at the Sixfields Stadium, Neil Sorvel put The Alex in front but veteran striker Marco Gabbiadini equalised with three minutes left for The Cobblers.
Notts County were held to a 1-1 draw by Wycombe Wanderers despite taking the lead through Marcel Cas. But new signing Craig Faulconbridge equalised with a minute to go for The Chairboys as both sides took a share of the points.
Click below for individual match summaries:
Bristol City 2-0 Blackpool
Cheltenham 0-2 Wigan
Colchester 1-0 Stockport
Huddersfield 0-2 Brentford
Luton 2-3 Peterborough
Mansfield 4-3 Plymouth
Northampton 1-1 Crewe
Notts County 1-1 Wycombe
Oldham 1-2 Cardiff
Port Vale 1-4 Tranmere
QPR 3-1 Chesterfield
Swindon 3-1 Barnsley
