Morgan Amaltifano and Saido Berahino saw West Brom win at Old Trafford for the first time in 35 years as they beat Premier League champions Manchester United 2-1 on Saturday.
The Baggies, whose last triumph at Old Trafford was a 5-3 success in the old First Division in 1978, inflicted a third defeat in six league games on David Moyes's United that left the hosts a lowly 12th in the table.
French midfielder Amaltifano, on loan from Marseille, opened the scoring with a fine solo effort just after the hour.
Wayne Rooney pulled the home side level with a free-kick but England Under-21 international Berahino scored the Baggies' second goal to earn a well-deserved win.
United substitute Marouane Fellaini had an effort rightly ruled out for offside and the hosts, who have not scored from open play since the first day of the season, created few chances.
Before the match, United manager Moyes referred to last Sunday's humbling 4-1 defeat at Manchester City as "embarrassing" and just four players that started that game were in the Scot's line-up for the West Brom clash.
West Brom's cause was hampered when Scott Sinclair, a winger on loan from City, limped off after just 12 minutes.
The visitors were finally sparked into life when Stephane Sessegnon burst past Shinji Kagawa and into the area from a short free-kick only for United's Michael Carrick to clear at the second attempt.
The Premier League champions finally threatened when Anderson picked out Nani with a raking pass and the Portuguese winger clipped in an impressive cross that just evaded Javier Hernandez for West Brom goalkeeper Boaz Myhill to gather.
Nani always looked dangerous and sent over a free-kick that found Rooney only for the striker to head straight at Myhill.
Just before the half hour, West Brom created a fine opening when Liam Ridgewell found Amalfitano on the left flank and the midfielder's cross was glanced just wide of goal by Berahino.
Anderson also had a low drive held by Myhill and Rooney headed over as United tried to end their first-half frustration.
United always looked more comfortable on the break and one quick counter-attack from Kagawa ended with the Japan midfielder crossing for Anderson to head against the bar.
A one-touch passing move then saw Anderson thread the ball through for Kagawa and he eked out the space for a shot only for the midfielder to fail to stretch Myhill.
Jonas Olsson flicked on a corner shortly before the break and Sessegnon thumped well off target from just a couple of yards as the visitors passed up another opportunity.
Belgian youngster Adnan Januzaj came on for Kagawa at the interval but fine work from Sessegnon opened up United once again shortly after the restart.
The Benin forward cut inside Alexander Buttner and Jonny Evans before feeding Berahino, whose low drive was turned wide by goalkeeper David de Gea.
However, West Brom scored eight minutes into the second period when Amalfitano picked the ball up on halfway, slipped past Rio Ferdinand and waited for de Gea to commit before lifting the ball over the keeper.
But the lead lasted just four minutes, with Rooney clipping in a free-kick from the left that was missed by Hernandez but flew into the far corner.
Youssef Mulumbu thumped a shot narrowly wide from just outside the area as West Brom showed they were not finished.
From an Amalfitano corner shortly afterwards Olsson beat Ferdinand to the ball and his header bounced away off the bar.
Amalfitano threatened with a bending free-kick that was pushed away from the top corner by de Gea.
But midway through the second period, the visitors took the lead again when Sessegnon clipped a ball to Amalfitano and youngster Berahino hit a powerful effort into the bottom corner.
Fellaini came off the bench and turned in from Nani's pass but was rightly ruled offside before Carrick and Januzaj failed to equalise with late efforts.