Manager Avram Grant insists the January transfer window has allowed West Ham to "see the light" in their bid to stay in the Premier League.
The Hammers take on Birmingham at Upton Park on Sunday, when they can take revenge over Alex McLeish's side who knocked them out of the Carling Cup last month in a hard-fought semi-final.
More importantly, a victory would see West Ham leapfrog Birmingham and jump out of the relegation zone.
Grant has warned his side, bolstered by January signings Gary O'Neil, Demba Ba, Wayne Bridge and especially Robbie Keane, that now is the time to step up the battle.
Grant said: "We see the light now but we need to fight for it. The important thing about this team is the development. We are learning from our mistakes. The football we are playing is better."