Brighton went ahead two minutes before half-time.
Jose Ulloa whipped in a cross which found Andrea Orlandi in front of goal and he flicked the ball home with the outside of his foot. The Bluebirds hit the woodwork four times but it was the Seagulls who breached their opponents’ defence when Ulloa pounced in injury time.
Brighton remain seventh.
While the Welsh side were going down to only their second home defeat of the season, Hull beat Blackburn 2-0 to claim their third successive victory to cut the gap at the top.
The Tigers went ahead in the 52nd minute when Mohamed Gedo slotted home a low shot from close range. Hull doubled their lead (67) when Quinn found Ahmed Elmohamady and he volleyed home.
Troubled Wolves dropped into the relegation zone following a 2-1 defeat at Barnsley, in a match where Wolves boss Dean Saunders opted to leave Republic of Ireland internationals Kevin Doyle and Stephen Ward on the bench.
Wolves started well and took a seventh-minute lead when Bjorn Sigurdarson beat the defence for pace and went round goalkeeper Luke Steele before coolly slotting the ball home.
But Barnsley levelled in the 49th minute when Chris Dagnall nodded home at the far post.
The Tykes’ dominance was then rewarded when Jacob Mellis put them ahead (73) and victory dumped Wolves into the bottom three.
Watford maintained their challenge with a 2-0 win at Mick McCarthy’s Ipswich to remain third.
The Hornets made an impressive start which was capped by Ikechi Anya’s 18th-minute goal.
Watford doubled their lead (72) when Nathaniel Chalobah rounded the goalkeeper and poked the ball home.
Crystal Palace remain fourth after a 2-1 win over Bristol City, who are now bottom of the table.
Palace went ahead in the 34th minute when the prolific Glenn Murray got ahead of his defender and volleyed home from a tight angle.
City improved in the second half but Palace substitute Stephen Dobbie curled home a long-range free kick (65) to make it 2-0.
The Robins pulled a goal back deep into injury-time when Jonathan Parr headed into his own net but there was no time to find an equaliser.
Charlton put a dent in Leicester’s challenge when they won 2-1 at the Foxes.
Radoslaw Majewski scored a first-half hat-trick as Nottingham Forest eased to a 6-1 win over Huddersfield who are slipping closer to the drop zone.