Tony Pulis tasted defeat in his first proper match as Middlesbrough manager as they were beaten by Aston Villa.
Pulis replaced Garry Monk hours before the Boxing Day win over Bolton, but four days later saw some of the problems faced by his predecessor as Robert Snodgrass' 75th-minute header earned Villa a 1-0 win.
Derby's stunning run of form continued and they moved into the top two thanks to a 2-1 win at Ipswich. Sam Winnall's brace had them comfortable and, although Joe Garner pulled one back, County made it five wins from their last six.
Bottom-of-the-table Birmingham upset promotion hopefuls Leeds as they ended their wretched recent run with a 1-0 home win, Jacques Maghoma tapping in with five minutes to go after Felix Wiedwald spilled Jota's shot.
Former Sheffield Wednesday striker Gary Madine silenced the Sheffield United boo-boys as his goal proved the difference in a 1-0 Bolton win at Bramall Lane.
Hull squandered a two-goal lead as they drew 2-2 at home to Fulham. Top-scorer Jarrod Bowen and Nouha Dicko had Nigel Adkins' men coasting, with Fulham hauling off two men before the break in response.
One of those sent on, Aboubakar Kamara, responded with a draw-earning brace, one of them from the spot and the second with four minutes left.
The clear improvements Chris Coleman has made to Sunderland were further evident as Aiden McGeady's goal secured a 1-0 win at Nottingham Forest, while managerless Sheffield Wednesday were beaten 2-0 at Brentford thanks to goals from Lasse Vibe and Florian Jozefzoon.