Scott McDonald capitalised on a goalkeeping error to enable promotion-chasing Middlesbrough to clinch a narrow win against Brighton.
Boro now lie fourth in the Championship, just five points behind leaders Southampton.
McDonald converted from close range when visiting keeper Casper Ankergren, under no pressure, spilled a left-wing cross from Joe Bennett.
Brighton sit just outside the play-offs after their first defeat in four games.
But they could have been in front early on when Craig Noone fired narrowly wide, before Kazenga LuaLua hit the left-hand post from 25 yards.
The home side had the lead soon after when Ankergren failed to deal with a seemingly innocuous cross and Middlesbrough continued to enjoy the upper hand in the first half. But they were dealt a blow when striker Marouane Zemmama limped off to be replaced by Malaury Martin.
The visitors began the second period with renewed energy and Gordon Greer should have done better when heading over from a LuaLua corner.
Matthew Bates then wasted a golden opportunity to double Boro's lead in the 53rd minute, volleying over the bar from 10 yards out from Tony McMahon's free-kick.
Boro continued to press forward but they were unable to find a second goal as substitute Bart Ogbeche and McDonald went close before the full time.