West Ham take on Premier League champions Man City on Saturday and they will need every one of their top players fit and firing. The Julen Lopetegui era at West Ham is up and running after two wins on the bounce ahead of Saturday’s massive test against Manchester City. A win is a win and the Hammers were always going to be a work in progress with a new manager, new philosophy and so many new players. But there is no hiding the fact West Ham have ridden their luck in victories over Crystal Palace and Bournemouth in the Premier League and Carabao Cup. Performance levels must improve quickly beca…