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.