The Seagulls put a dampener on Cardiff manager Malky Mackay's birthday celebrations as goals from former Swansea midfielder Andrea Orlandi and Jose Ulloa secured a 2-0 victory at Cardiff City Stadium.
Orlandi opened the scoring when he turned in a David Lopez cross just before half-time before Ulloa sealed the win in stoppage time to boost Albion's play-off aspirations and inflict Cardiff's second home defeat of the season.
But Mackay, who turned 41 on Tuesday, will have been left wondering how his side failed to make the most of a host of chances as they were denied four times by the woodwork and by a superb performance from Brighton keeper Tomasz Kuszczak.
This was Cardiff's first loss in 10 games and their lead at the top of the Championship has been cut to five points after Hull's win over Blackburn, although the Welsh club have a game in hand on their Yorkshire rivals.
Egyptian duo Gedo and Ahmed Elmohamady both struck in the second half to give high-flying Hull a 2-0 win - their third at home in eight days - and saw them close the gap on leaders Cardiff to five points.
It was a particularly sweet victory for manager Steve Bruce, who brought Gedo in on loan from Al Ahly when DJ Campbell pulled the plug on a move to the Tigers in favour of Blackburn.
Campbell started on the substitutes' bench but that did not save him from the Hull fans' ire.
Rovers had not lost in their last six and were coming off the back of a memorable FA Cup victory over Arsenal at the Emirates Stadium, however they were indebted to Jake Kean's magnificent one-handed save from David Meyler in the first half.
Gedo grabbed his third in as many games by side-footing home Stephen Quinn's cross and only another splendid save from Kean prevented that lead from being doubled.
But the Tigers made sure of the points when Elmohamady fired a first-time volley back past Kean just after the hour mark.
A goal in each half helped Watford gain a vital 2-0 victory at Ipswich in the battle for promotion which saw them close the gap on Cardiff to eight points.
The visitors flew out the traps with Jonathan Hogg hitting the crossbar before Ikechi Anya scored for the second time in four days with a fine curling finish.
Nathaniel Chalobah then put the game to bed in the 73rd minute, slotting past Stephen Henderson to secure three valuable points in the Hornets' push for promotion.
Glenn Murray helped himself to yet another goal to keep Crystal Palace's promotion bid on track with a 2-1 win over Bristol City.
The country's leading marksman took his tally for the season to 28 with a superb first-half opener.
Stephen Dobbie struck after the break to seal Palace's third win in four outings and dump sorry Bristol City on to the foot of the table despite a late own goal by Jonathan Parr.
Middlesbrough continued to struggle for the form required to get their promotion push back on track as they played out a goalless draw at Burnley.
Tony Mowbray's play-off occupants spent the vast majority of the 90 minutes at Turf Moor on the back foot, with goalkeeper Jason Steele saving well from Charlie Austin and Dean Marney in the first half.
But Burnley, 10th in the table and seven points behind their opponents with a game in hand, could not turn their dominance into the required amount of clear-cut chances.
Yann Kermorgant returned to the King Power Stadium to haunt Leicester as the Frenchman scored one and created another in Charlton's 2-1 victory.
The 31-year-old, who also scored in the Addicks 2-1 victory in the reverse fixture back in August, was playing in Leicester for the first-time since his costly play-off semi-final penalty miss two years ago during an ill-fated spell with the Foxes.
Booed throughout, Kermorgant, almost inevitably, had the last laugh as Charlton performed a textbook smash-and-grab raid against a Leicester side who dominated from start to finish.
Both Kermorgant's first-half opener and Danny Haynes' winner came completely against the run of play, while the returning Chris Wood's leveller was not enough to earn his side anything from the game.
Nottingham Forest fans were treated to a memorable evening as the second Billy Davies era sparked into life with Radoslaw Majewski scoring a first-half hat-trick in a 6-1 win against Huddersfield.
Davies' last triumph at the City Ground saw Scunthorpe dismissed 5-1 in April 2011 and nearly two years later the Scot mopped up the applause as a largely different group of players went one better.
Majewski was a key figure in Davies' previous reign and the Pole rolled back the years to cancel out James Vaughan's early opener with his first goal of the season.
Elliot Ward completed the swift turn-around with a confident header before Majewski thumped in two more goals before the half-time whistle.
New Huddersfield manager Mark Robins was left under no illusions of the task facing him as Henri Lansbury strolled through his defence to complete the rout shortly after the break, with substitute Darius Henderson adding insult to injury deep into stoppage time.
David Flitcroft continues to have the Midas touch at Barnsley after they delivered a fourth straight Championship win to move out of the relegation zone after beating Wolves 2-1 at Oakwell.
The Reds, who also set up an FA Cup quarter-final with Manchester City at the weekend, overcame an early deficit with second-half goals from Chris Dagnall and Jacob Mellis and extended a remarkable run of form under Flitcroft.
They have now won eight of their last nine games and the last six in all competitions and survival, which looked a long shot under former boss Keith Hill, is now in their own hands with 14 games to go.
Wolves take their place in the relegation zone, with manager Dean Saunders still searching for a first win in charge after seven games.
Jamie Ward's 10th goal of the season salvaged a 1-1 draw for Derby against Bolton at Pride Park.
After the same score at Nottingham Forest on Saturday, it was Bolton's second 1-1 draw in the east midlands in the space of three days and Dougie Freedman's side are still without an away win since November.
For Derby, it was a third stalemate in four outings and they have won just one of their last seven Championship matches.
Relegation rivals Birmingham and Sheffield Wednesday could not be separated at St Andrew's as both sides were forced to settle for a point in their battles against the drop from the Championship.
Ultimately, a game which could have gone either way hinged on two moments in either half.
Blues goalkeeper Jack Butland pulled off a contender for save of the season in the 11th minute as he incredibly clawed out a header from Owls centre-back Miguel Llera which appeared to have been beyond him.
Just as amazingly, Blues somehow failed to take lead midway through the second half.
An unmarked Nikola Zigic - included in boss Lee Clark's XI having been dropped for Saturday's 4-0 defeat to Watford following his lacklustre efforts in training - failed to anticipate Chris Burke's cross and diverted the ball wide from merely four yards.
The stalemate, Birmingham's first clean in 20 games in all competitions, keeps both sides just above the relegation zone, with a resurgent Wednesday now having tasted defeat just once in 11 league matches.
Peterborough produced a masterful attacking display to over-run FA Cup quarter-finalists Millwall 5-1 and move off the foot of the Championship table.
The Lions, suffering what could be seen as an FA Cup hangover, were second best for the majority of the game at the New Den and their evening was compounded when Shane Lowry was sent off in the second half.
Lee Tomlin bagged a brace and George Boyd pulled the strings for Posh, who leapfrogged Bristol City to move to within five points of safety.
Tomlin stuck early with James Henry equalising for the home side before Tommy Rowe and Nathaniel Mendez-Laing scored either side of a second goal from Tomlin and Boyd capped a wonderful display by adding a fifth late on.
Millwall, despite their run to the last eight of the FA Cup, have not won in the league since New Year's Day.