Romelu Lukaku scored his 12th goal in 11 FA Cup games as an uninspired Manchester United beat Brighton to reach the semi-finals.
Lukaku headed in a first-half cross from Nemanja Matic, who sealed victory late on when he nodded in Ashley Young’s free-kick.
Victory maintained realistic United hopes of a trophy after Tuesday’s Champions League elimination by Sevilla, as well as their record of not having conceded a goal in this season’s FA Cup.
But Jose Mourinho’s side struggled through the second half, as Brighton had several chances to force extra-time before Matic finally put the tie to bed.
Home fans, angry about the unadventurous performance in defeat by Sevilla, became increasingly tetchy as the game wore on.
Jurgen Locadia, Brighton’s £14m record signing, had four chances to equalise, with goalkeeper Sergio Romero saving the first two before the Dutchman headed over wastefully from Solly March’s cross.
He then had a shot blocked by Chris Smalling, who had hit the post for United before Lukaku’s goal.