With Bournemouth and Watford not kicking off their games against Ipswich and Derby respectively until later on, Boro stole a march on their rivals thanks to Patrick Bamford's 17th strike of the season.
The on-loan Chelsea striker bent a low effort into the bottom corner in the 20th minute and that was enough to send Boro two points clear at the summit.
The defeat for Wigan, who squandered second-half chances, leaves them five points adrift of safety.
It was also a good afternoon for Norwich who are kept out of the top two on goal difference alone after a 1-0 win at Brighton.
It was exactly one year ago this weekend when the Canaries sacked Chris Hughton, but there was to be no revenge for the Brighton boss as his new side were downed by Bradley Johnson's cool finish just after the hour.
Brentford also moved back into the top six after a 4-1 win over local rivals Fulham.
The Bees surged into a two-goal lead thanks to Stuart Dallas' brace, grabbing a goal in either half with two fine finishes.
Ross McCormack's penalty got the Cottagers back in it with 20 minutes to go but late efforts from Alan Judge and Ramallo Jota settled it for the Bees.
Wolves made their move into the top six with an impressive 2-1 win at Nottingham Forest.
Kenny Jackett's men went in front just 20 seconds after the restart with a fine effort from distance by Benik Afobe and Bakary Sako's 72nd-minute penalty ensured they moved up to sixth in the league despite Dexter Blackstock's late strike.
Millwall breathed fresh life into their survival fight with a late 2-1 come-from-behind win against 10-man Charlton.
Goals from Magaye Gueye and Jos Hooiveld in the final 11 minutes gave the Lions the points after Alou Diarra put Charlton, who had Chris Solly sent off, ahead.
Elsewhere, Rotherham's plight is more precarious now after they went down 2-1 at Birmingham
Bournemouth will have the chance to reclaim top spot when they take on Ipswich at 5.15pm, while Watford make the trip to Derby at 7.45pm.
Source : PA
Source: PA