Championship leaders Cardiff crashed to a 2-1 defeat at Middlesbrough, while promotion rivals Hull regained second place with a 5-2 demolition of Birmingham on Saturday.
Malky Mackay's table-toppers saw their lead cut to five points following their first defeat in 10 away league games.
Former England midfielder Kieron Dyer's first league goal since 2007 put the hosts ahead in the 13th minute before on-loan Newcastle forward Sammy Ameobi marked his debut with the second four minutes later.
Aron Gunnarsson's seventh goal of the campaign reduced the deficit in the 67th minute, but there was no way back for Cardiff as Middlesbrough remain in the hunt for a play-off berth.
While Cardiff stumbled, Steve Bruce's Hull closed the gap on the leaders after an emphatic win over struggling Birmingham at the KC Stadium.
George Boyd and Mohamed Gedo both scored twice for the Tigers with Robert Koren also on the scoresheet as they bounced back from last weekend's 4-1 defeat at Bolton.
Hull were two goals to the good after just 11 minutes with Boyd scoring after just 46 seconds and Gedo firing home from 12 yards in a blistering start.
Boyd added his second just before the half hour mark as Hull secured a three-goal cushion before Koren struck after the break with Gedo beating Jack Butland again in the 76th minute.
Peter Lovenkrands and Christopher Burke scored late goals for Birmingham but Hull had done enough to take advantage of third placed Watford's 1-1 draw against Wolves on Friday.
Fifth-placed Leicester slipped up in their promotion bid as they lost 1-0 to Ipswich.
Substitute David McGoldrick claimed an 85th-minute winner for Mick McCarthy's side.
Leonardo Ulloa hit a hat-trick as Brighton continued their promotion push with a 4-1 win over Huddersfield.
Blackburn were blown away by a first-half Dwight Gayle hat-trick before Peterborough withstood a second-half fightback to climb off the bottom of the table with a 3-2 win at Ewood Park.
Leeds earned a 1-0 win over Millwall at Elland Road thanks to Stephen Warnock's 72nd-minute penalty after Ross McCormack saw his earlier spot-kick saved by Lions goalkeeper David Forde.
Craig Dawson struck the decisive goal for Bolton in the 3-2 win over Barnsley as they stepped up their play-off push by extending their unbeaten run to six matches.
David Ngog and Jay Spearing scored for Bolton before Tomasz Cywka and Chris O'Grady levelled the scores. Dawson then fired the winner in the 59th minute.
Elsewhere, Burnley beat Charlton 1-0 thanks to Charlie Austin's first-half goal while Blackpool drew 0-0 against Bristol City.