With West Ham sitting bottom of the Premier League the result, which ends United’s 29 match unbeaten run, will relieve pressure on under-fire manager Avram Grant.
The Israeli is fast developing a reputation as a cup specialist having guided Chelsea to the Champions League final in 2008 and Portsmouth to the FA cup final last year.
But the night could have ended differently had Robert Green not pulled off a stunning save down to his right-hand side to push Gabriel Obertan’s low shot onto the post in the seventh minute.
From that point on however the home side dominated and thought they had taken the lead in the 16th minute when Victor Obinna’s deflected shot flew into the net, only for it to be ruled offside.
But Spector put the home side ahead six minutes later when he got in front of Darren Fletcher to head home Obinna’s dinked cross for his first goal in English football.
Spector, who made eight career appearances for Manchester United in two years, scored his second in the 37th minute after capitalising on a slip from Fabio to smash the ball home from seven yards.
Sir Alex Ferguson, who rested the majority of his first team players ahead of a busy December, would have expected more from his young players and brought Federico Macheda on for the ineffectual BÃƒÂ©bÃƒÂ© at half time.
However, United continued to struggle and went 3-0 behind when Cole headed home at the near post in 55th minute after good play by Obinna down the left hand side.
Cole, who had not scored in his previous 19 games, grabbed his second in the 66th minute as he turned Evans in the box and drilled a low shot past Tomaz Kuszczak after more trickery from Obinna on the left wing.
West Ham boss Grant praised the performance of his side, who are now unbeaten in five home matches, after the match. “It’s very special,” he said. “To perform like this against the best team today in the country and score four goals, what more can I ask?
“Today we played fantastic and also scored and we kept a clean sheet. So I’m very happy. I thought we could win, but not by that score.”
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