West Brom midfielder Darren Fletcher thinks the game plan to frustrate Manchester United worked to perfection in the 1-0 win at Old Trafford.
Fletcher, who left Old Trafford for the Baggies earlier this year, oversaw a win which came thanks to Chris Brunt's free-kick, which was deflected in by team-mate Jonas Olsson.
Robin van Persie, making his first start since February 21, then missed a penalty for the hosts shortly after Albion took the lead.
Defeat leaves Manchester United in danger of missing out on an automatic Champions League spot, while West Brom are on a three-match unbeaten run.
“We worked on making it difficult,” Fletcher told Sky Sports.
“We’d have liked to have played more but sometimes it doesn’t work out like that.
“United keep the ball very well but we tried to make sure they were playing in front of us and not between the lines and not wide. We work hard at set pieces all the time and thankfully one’s come off today.
“We knew we’d have to ride our luck and we did that today. With the way the results went today it’s a massive three points for us.”
West Brom’s victory means they have now secured back-to-back victories at Old Trafford for the first time since 1959.
“The manager said before the game that we’d done it before so you’ve got to believe it,” Fletcher added.
“I’ve noticed that the biggest thing about coming to Old Trafford is teams are beat before they come here. You have to believe you’re going to win. You know you are going to have to ride your luck.
“We spoke about trying to win individual battles. Boaz Myhill has saved a penalty as well and sometimes you need that. We’re not coming here and saying we dominated the match.
“The game plan was to frustrate them and to sneak a goal worked.”
Fletcher spent 12 years at Old Trafford before moving to the Hawthorns and he revealed he got confused moments before the kick-off.
He said: “Before the game I lined up on the wrong side of the tunnel. I knew I’d do something.”
Despite helping to inflict defeat on his former team, the Soctland midfielder had some words of encouragement for Louis van Gaal’s side when asked whether they could challenge for the title next season.
He said: “I do. The goal all along this season was to finish in the top four and for the club to get back in the Champions League.
“Chelsea were always going to be tough to catch this year and it’s the first year of a new manager. There’s going to be a transition. They’ve got to believe.
“Manchester United need to be challenging and just accept top four is not good enough. I think for one season you can accept it but next year the fans and I’m sure the players in there will be demanding that they go and win the title. “