Cardiff's bid to join Welsh rivals Swansea in the Premier League suffered a setback when the leaders of the second-tier Championship went down to a 2-0 defeat at home to Brighton on Tuesday.
The Bluebirds remained top of the table but saw their lead cut to five points after goals from Andrea Orlandi and an injury-time effort from Jose Ulloa gave the Seagulls victory in a match where Cardiff hit the woodwork four times.
Brighton remained seventh.
Second-placed Hull won for the third match in a row to close the gap on Cardiff after a 2-0 win at home to Indian-owned Blackburn Rovers, unable to follow up their FA Cup victory against Arsenal.
Mohamed Gedo slotted home from close range in the 52nd minute before a 67th minute volley from Ahmed Elmohamady secured all three points for the Tigers.
Watford, still with hopes of securing one of the two automatic promotion places at the end of the regular season, remained third, three points behind Hull, with a 2-0 win away to Ipswich Town.
Ikechi Anya gave the visitors an 18th minute lead at Portman Road before Nathaniel Chalobah rounded the goalkeeper for a well-taken second goal in the 72nd minute.
Elsewhere Billy Davies's second spell as manager of Nottingham Forest took flight with a 6-1 thrashing of Huddersfield at the City Ground.
Davies's last home triumph with Forest saw Scunthorpe beaten 5-1 in April 2011 but, with a largely different group of players, the Scot went one better on Tuesday with Radoslaw Majewski's first-half hat-trick doing the bulk of the damage for the eighth-placed Midlands club.
It was a different story for Millwall as the Lions, fresh from knocking non-league Luton out of the FA Cup at the weekend, were brought back down to earth by a 5-1 loss at home to Peterborough, managed by Darren Ferguson, son of Manchester United boss Alex.
'The Posh' climbed off the bottom of the table at the New Den in a match where, with Peterborough leading 4-1, Millwall had Shane Lowry sent off for a professional foul on Dwight Gayle.
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