Leeds United looked set to reclaim first place later in the day but threw away a three-goal lead at home to Cardiff City to draw 3-3.
Preston North End is now 10 points behind Marcelo Bielsa's side after a 2-1 win over Luton Town, while Brentford leap-frogged Fulham into fourth with a slender 1-0 win.
At the other end of the table, rock-bottom Barnsley registered a remarkable 5-3 win over Queens Park Rangers but Middlesbrough slumped to a 3-1 defeat at Swansea City.
AUSTIN INSPIRES BAGGIES COMEBACK
Charlie Austin took his tally for the season to eight with a brace to help West Brom record a vital win at Birmingham City.
Slaven Bilic's side looked set for a first defeat in 12 league games after Lukas Jutkiewicz and Harlee Dean had scored either side of Grady Diangana's goal.
Austin drew his side level three minutes after being introduced, though, when he flicked up Jake Livermore's pass and rifled a half-volley past Connal Trueman.
The 30-year-old sealed all three points nine minutes from time, powering home Darnell Furlong's cross with his head.
LEEDS CAPITULATES AGAINST BLUEBIRDS
Leeds conceded three goals inside the final 30 minutes to miss the opportunity to quickly reclaim top spot from the Baggies.
Helder Costa gave the hosts a wonderful start at Elland Road, scoring after six minutes, before Patrick Bamford struck twice to open up a commanding lead.
However, Lee Tomlin gave the Bluebirds hope with a goal on the hour mark to spark an unexpected comeback.
Sean Morrison added another with eight minutes remaining, before receiving his marching orders four minutes later for a late tackle.
The numerical disadvantage did not daunt the visitors, however, as Robert Glatzel struck with two minutes remaining.
STOCKLEY FIRES PRESTON INTO THIRD
Jayden Stockley scored with six minutes remaining to help Preston beat Luton and climb to third in the table.
Paul Gallagher opened the scoring early on, slotting home after his penalty had been saved, before James Collins levelled from the spot.
Brentford, meanwhile, is a point behind Preston in fourth after Bryan Mbeumo scored the only goal of the game against Fulham.
Sheffield Wednesday is level on points with the Bees, the Owls cruising to a resounding 4-0 win over Nottingham Forest at The City Ground thanks to a first-half hat-trick from Jordan Rhodes.
CHAPLIN TREBLE LIFTS CLOUDS OVER BARNSLEY
Barnsley moved to within four points of safety as Conor Chaplin's hat-trick helped it to a stunning win over QPR at Oakwell.
Cauley Woodrow and Bambo Diaby were also on target in what was only the Tykes' third league win of the campaign.
Fellow struggler Stoke City and Wigan Athletic was held to 0-0 and 1-1 draws by Reading and Huddersfield Town respectively.
Andre Ayew scored twice in Swansea's comfortable win over Middlesbrough, while Bradley Johnson and Adam Armstrong helped Blackburn Rovers to a 2-0 triumph at Bristol City.