Two second-half goals from Spanish duo Andrea Orlandi and David Lopez secured the Seagulls their first away win in five attempts that moved them up to fifth in the npower Championship table.
For Tony Mowbray's Boro, they are down to 10th after their sixth defeat in their last seven games and lie eight points off the top six, and just six points off the bottom three.
Both goalkeepers had a chance to test their handling in the opening stages. Lopez's deflected shot was comfortably held by Jason Steele before Richard Smallwood's drilled effort was saved down low by Casper Ankergen, who was making only his second Championship appearance of the season.
But the early action was not a sign of things to come, with neither of the out-of-form sides able to find any kind of rhythm.
Dean Hammond went close to breaking the deadlock in the 50th minute after he was found in the area by Jose Ulloa's terrific pass but the midfielder was unable to steer his header on target.
It was the visitors who eventually broke the deadlock. Hammond squared from the right for Orlandi, whose run into the area had gone unnoticed by the Boro defence, and the Spanish midfielder side-footed past Steele for his fifth league goal of the campaign.
They had Gordon Greer to thank for preserving their lead as the defender made two vital blocks in as many minutes to deny Scott McDonald and then Curtis Main from getting shots at goal.
Gus Poyet's side sealed victory when Lopez was sent clear by Liam Bridcutt and he lobbed the on-rushing Steele to ensure his side remained in the play-off places.
- Sports & Recreation
- Andrea Orlandi