West Ham United boss Sam Allardyce identified Eliaquim Mangala as Manchester City's weak point for Saturday's shock win.
The £32million summer signing from Porto had a torrid afternoon and could not cope with the powerful forward line of Diafra Sakho and Enner Valencia.
Allardyce said: "I think they leave him exposed. He's only just joined.
"They don't protect him and he's only just got here. Vincent Kompany is used to it, he's been at this level for such a long time. This lad's not, he's finding his feet and we made big strides down the left and caused them lots of problems."
He added: "Maybe there should have been a bit more protection from other players. That wasn't there and we exposed that."
