The Iron pulled clear of the Latics after they crashed 3-0 at Vale Park.
Danny Whitaker, George Pilkington and Leon Constantine scored for the Valiants.
Oldham remain second, as Nottingham Forest again failed to capitalise.
A controversial stoppage-time penalty from Wesley Hoolahan earned Blackpool a point.
Hoolahan was forced to take the spot-kick twice, as he levelled Junior Agogo's opener.
Forest drop down to fourth, with Yeovil now the closest challengers to Bristol City - who weren't in action on Tuesday night due to the Johnstone's Paint Trophy involvment - after their 2-0 success at Bournemouth.
Wayne Gray and Leon Best earned the Glovers the points at Dean Court.
Tranmere's play-off hopes were hit by a 2-2 home draw with Cheltenham, with Rovers needing a late equaliser to rescue a point.
Keith Lowe and Kayode Odejayi had put the Robins two goals ahead at Prenton Park, but the Wirral outfit levelled thanks to strikes from Chris Shuker and Chris Greenacre.
Leyton Orient were 5-2 victors in a remarkable London derby at Millwall - a match which saw them race into a three-goal lead within the opening 12 minutes.
Ryan Jarvis - on-loan at the Os from Norwich - ended up with a hat-trick for the relegation-threatened side.
Brighton beat Gillingham, who travel to Glanford Park on Saturday, thanks to a goal from Bas Savage
And bottom-side Rotheram crashed to another defeat, losing 3-2 at home to Yorkshire rivals Huddersfield.