Leeds started its clash with third-bottom Wigan holding a two-point lead at the summit, but a Pablo Hernandez own goal was enough for Wigan to pull off a repeat of its victory at Elland Road last season.
A Donervon Daniels own goal and Semi Ajayi's header moved Albion a point clear of Leeds, while Fulham is just three points adrift of Marcelo Bielsa's men after their 3-2 defeat of Huddersfield Town.
Just six points separate the top six after wins for Brentford and Bristol City, with Nottingham Forest slipping to fourth after it went down 2-1 at Birmingham City.
Charlton Athletic's 2-1 win over fellow struggler Barnsley moved it four points clear of the relegation zone.
Preston North End was held to a 1-1 home draw Swansea City, while it was also all square in the encounters between Sheffield Wednesday and Millwall and Middlesbrough and Blackburn Rovers.
DEJA VU AT ELLAND ROAD FOR TOOTHLESS LEEDS
Leeds mounted a storming fightback to beat Millwall in midweek and a home encounter with Wigan appeared to be a great opportunity to build on what was its first win in four league matches.
Yet Wigan inflicted a costly 2-1 defeat late in the Yorkshire club's bid for automatic promotion last year and Paul Cook's side headed back to Lancashire with three precious points again this time around.
Joe Williams's corner deflected off Hernandez and into the net just before the hour-mark and wasteful Leeds was unable to respond, slumping to a third loss in four.
BAGGIES RESPOND, FIVE-STAR BEES THUMP HULL
West Brom was beaten at Cardiff City on Wednesday (AEDT) after losing its previous Championship encounter with Stoke City, but there was no slip-up against bottom side Luton at The Hawthorns.
Brentford had failed to score in its previous three matches in all competitions, but Said Benrahma scored a hat-trick as it thrashed Hull City 5-1 at KC Stadium to move four points behind Leeds.
All five goals came in the first half of Fulham's 3-2 victory over Huddersfield, while Bristol City has won four in a row in the league without conceding after a 1-0 success at Queens Park Rangers.
CHARLTON CLAIMS PRECIOUS RARE WIN
Only a second Championship win in 18 games moved Charlton above Stoke, hammered by Derby County on Saturday (AEDT), and Huddersfield.
Lyle Taylor and Andre Green were on target for the Addicks, leaving Barnsley seven points behind a Stoke side sitting just above the bottom three.