Tony Pulis believes his West Brom side got the luck any team needs if they are to come away from Old Trafford with all three points in Saturday's 1-0 victory.
West Brom condemned Manchester United to a third straight Premier League defeat thanks to Chris Brunt's free-kick on the hour, which took a wicked deflection off Jonas Olsson to beat David de Gea.
United dominated the game from start to finish, but could not break a stubborn West Brom outfit down and Robin van Persie missed a penalty 18 minutes from time to round off a disappointing day for Louis van Gaal.
And Pulis admitted the visitors - who also won at Old Trafford last season - were slightly fortuitous to escape with a victory that all-but secures their top-flight status for another year.
"To come here, you have to be resilient, you have to be well set-up," said the head coach.
"We worked very hard this week to make sure people were in the right spots to stop United from penetrating.
"You still need a bit of luck and we had that - we had the run of the ball.
"Beating United at Old Trafford is brilliant and something the players will take on board. It's a great three points [but] now we move on. We've got three very tough games left.
"The fact 50-60 per cent of the players in the team came here and won last year certainly gave us a psychological edge."
Boaz Myhill capped an outstanding performance in the West Brom goal with his penalty save from Van Persie, and Pulis feels it would have been an injustice had the Dutchman scored.
Referee Anthony Taylor pointed to the spot after Saido Berahino blocked Antonio Valencia's cross with his arm, even though the official's assistant gave a corner.
"It wasn't a penalty, that was very disappointing. It was a yard outside the box," Pulis added.
