Nicolas Anelka's two goals at the end of the first half ensured that West Bromwich Albion went into break leading West Ham United 2-1.
It was West Ham who took an early lead though, as Joe Cole latched onto a flick-on by Carlton Cole and played a neat one-two with Kevin Nolan before rifling a low shot underneath the reach of Ben Foster.
However, the hosts were forced into a change as early as the eighth minute when James Tomkins left the field with a groin injury and was replaced by Guy Demel, who joined fellow full-back George McCartney in a makeshift central defensive pairing for the hosts.
Jonas Olsson tried to take advantage almost immediately with a header at the far post, but Jussi Jaaskelainen gathered easily, while at the other end C. Cole and Nolan both saw their shots blocked by Liam Ridgewell.
C. Cole continued to cause problems for the West Brom defence and nodded narrowly over the bar from Matt Jarvis's corner as the home side looked to extend their advantage.
Demel then swivelled and struck the outside of the post from close range in the 30th minute after the visitors had failed to clear crosses by Jarvis and J. Cole before Mark Noble sent a 25-yard free kick just wide of Foster's right hand post.
For all of West Ham's chances, the visitors were level in the 40th minute when Anelka latched onto Chris Brunt's through ball and held off the challenge of Joey O'Brien to lift a composed finish over the trailing leg of Jasskelainen.
Five minutes later, Anelka poked the ball home from close range after C. Cole had blocked Olsson's header on the line as the visitors turned the game on its head.
