Championship results: West Brom drop points at Wigan, Cardiff suffer first defeat under Neil Harris
Leeds’ 2-0 win over Hull 24 hours earlier saw them leapfrog the Baggies at the summit.
But West Brom could only salvage a draw against 23rd-placed Wigan, who went ahead from a Sam Johnstone own goal, before Charlie Austin equalised for Slaven Bilic’s men.
Leeds lead West Brom at the top on goal difference, with both sides on 46 points.
Elsewhere, Neil Harris’ unbeaten start as Cardiff boss came to an end with a 2-1 defeat at Brentford.
Bryan Mbeumo and Ollie Watkins goals gave Brentford a comfortable advantage as Marlon Park pulled one back for the visitors in the 64th minute.
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A win would have brought the Bluebirds level on points with sixth-placed Nottingham Forest.
Gerhard Struber is still looking for his first win as Barnsley manager following his side’s 1-1 draw with Reading.
Cauley Woodrow gave the Tykes the lead just before the hour mark, before Lucas Joao equalised 14 minutes from time.
Swansea and Blackburn played out a 1-1 draw in Wales as both teams finished the game with 10 men as Tom Carroll and Bradley Dack were sent off for two bookable offences at separate times in the second-half.
Chris Martin netted a late penalty to earn Derby a draw and deny Sheffield Wednesday a third successive win.
Birmingham suffered a 2-0 home defeat to QPR thanks to goals from Grant Hall and Bright Osayi-Samuel.