Danny Welbeck came back to haunt his old club once again as Albion deservedly reached the fourth round of the Emirates FA Cup.
Albionâs captain for the day scored his eighth goal against Manchester United and ninth of the season midway through the second half after Brajan Gruda had given Albion an 11th-minute lead at Old Trafford.
Jason Steele, one of six changes made by Fabian Hurzeler, made two important early saves but after Grudaâs third goal of the season Albion grew in confidence and Welbeckâs thunderous left-foot finish to double their lead was fully deserved.
Brajan Gruda fires Albion in front at Old Trafford. đˇJames Boardman
Benjamin Sesko gave United a lifeline with a late header but they finished with ten men after substitute Shea Lacey was sent off and Albion showed commendable composure to see the game out.
Steele was making his first start since the Carabao Cup tie against Arsenal in October, and he was soon showing his shot-stopping skills, spreading himself to block when Diego Dalot got in before getting a touch at full stretch to keep out Bruno Fernandesâs 25-yarder, which had taken a deflection off Sesko.
Albion rode the early storm and took an 11th minute lead. The move began when Jack Hinshelwoodâs excellent cross-field pass found Ferdi Kadioglu in yards of space on the left. He spotted Welbeckâs run in the inside-left channel and Welbeck chipped the ball to the back post. Georginioâs header was hacked off the line by Lisandro Martinez but only to Gruda, who whipped a right-foot shot from eight yards into the roof of the net.
It should have been 2-0 three minutes later. Senne Lammensâ pass was intercepted by Welbeck, but the United keeper recovered to parry away his shot and Georginio was offside when he tried to fire in the loose ball.
Brajan Gruda celebrates after scoring his third goal of the season. đˇJames Boardman
As Old Trafford grew more tense Albion grew in confidence. Joel Veltman belted a right-foot shot from 25 yards just wide and after another good move Welbeck fired into the side netting. Bruno Fernandes and Matheus Cunha saw efforts go narrowly wide but after a shaky start Albion deserved their half-time lead.
Veltman was having a productive game and when Grudaâs free-kick dropped to him 15 yards out he had time and space but lashed a left-foot shot high into the stands. It was a disappointing effort but indicative of Albionâs positive start to the second half.
And it was rewarded on 64 minutes with a second goal. Grudaâs sideways pass was controlled with his right foot by Welbeck and lashed into the roof of the net with his left from 15 yards out. Credit in the build-up to Veltman, who began the move with his pick-out of Gruda wide on the right.
Manuel Ugarte sends Georginio tumbling. đˇJames Boardman
United set up a nervy finish when Sesko headed Fernandesâ corner in at the far post and Old Trafford found its voice again. Albion regrouped, their task in seeing the game out made easier when Lacey picked up a second yellow card and headed down the tunnel distraught. His reaction was in sharp contrast to those of Albionâs fans as they celebrated at full-time.
Albion: Steele, Veltman (Ayari 77), Coppola, Boscagli, Kadioglu, Gruda (Watson 90+1), Gross, Hinshelwood, Gomez (van Hecke 77), Rutter (Kostoulas 81), Welbeck (Mitoma 77).
Subs not used: Verbruggen, Dunk, Tasker, Howell.
Referee: Simon Hooper.