كتب : Hatem Maher
United are in charge of the league table with 44 points, two ahead of defending champions Chelsea.
At the Upton Park, West Ham new manager Alan Curbishley made a winning start as his side overcame the wasteful United.
United will be left ruing their missed chances through Cristiano Ronaldo, Ryan Giggs and Frenchman Louis Saha.
Nigel Reo-Coker struck the winner in the 75th minute when he poked home from close range after being set-up by Teddy Sheringham's low cross.
Elsewhere, a sensational volley by Didier Drogba earned English champions Chelsea a hard-fought 3-2 away victory over Everton.
Spanish midfielder Mikel Arteta put the hosts ahead in the 38th minute from the penalty spot after Khalid Boulahrouz hauled down Victor Anichebe inside the area.
German international Michael Ballack leveled the score four minutes after re-start when he curled a brilliant free-kick into the right corner of the net.
Nigerian defender Joseph Yobo restored the lead for Everton four minutes past the hour mark when he rose above his marker Michael Essien to head home a corner-kick.
Frank Lampard equalized again for Blues nine minutes from time after hitting a powerful drive into the right top corner of the net.
Six minutes later, the in-form Drogba controlled Andrei Shevchenko's header before firing an unstoppable volley past Everton keeper Tim Howard.