City had gone 2 points clear thanks to Friday's excellent win at Loftus Rd but Wigan did a professional job and took all three points from Northampton Town.
There was better news though from Oldham and Bristol City. Both teams could only manage to draw so a gap has appeared.
Wigan lead on 44 points from 20 games, City are second with 43 points from 20 games. Oldham in third have 39 points from 20 games while Bristol City have 38 points from 19 games.
Crewe in 5th have 35 points and QPR in 6th are a massive 13 points behind City with 30 points. Both Crewe and QPR have played 20 games.
The next league action sees the match of the day at Ninian Park. Cardiff v Bristol. It's live on Sky and could be classed a proverbial 6 pointer. A Cardiff win would see an 8 point gap open up, a win for the Wurzels would close it to 2 points and they have a game in hand.