Manuel Pellegrini's side are unbeaten in 13 matches across all competitions, and will be eager to extend that run when welcoming Sam Allardyce's Premier League strugglers to the Etihad Stadium for the first leg of their semi-final.
Although City were held to a 1-1 FA Cup draw at Blackburn Rovers on Saturday, the two-time winners will be confident of gaining an advantage over a West Ham side in the midst of an awful season.
West Ham, who have never won the League Cup, head into the encounter in woeful form, having won just one of their last nine games.
That came last month, when Allardyce's side claimed a surprise 2-1 victory at Tottenham to reach the last four.
While that triumph was welcome, a much-changed West Ham side suffered a humiliating 5-0 FA Cup defeat at Championship side Nottingham Forest at the weekend to deepen the gloom around Upton Park.
Allardyce has since received a vote of confidence from the club's hierarchy, but the former Newcastle United and Bolton Wanderers manager will know his injury-hit team must show significant improvement if they are to prevail against City.
The London club are without a number of key players, including striker Andy Carroll (foot) and defenders James Tomkins (groin) and James Collins (calf).
Winston Reid (ankle) and Ricardo Vaz Te (shoulder) also remain on the sidelines, while captain Kevin Nolan is suspended.
Reflecting on the 5-0 loss at Forest, Allardyce said: "Nobody wants to get beat and we certainly don't want to get beat 5-0, but at the end of the day the semi-final against Manchester City is more important."
Sergio Aguero (calf) and Dedryck Boyata (suspension) are out for City, but Micah Richards, Stevan Jovetic and Martin Demichelis (all hamstring) are nearing full fitness.
Jack Rodwell also missed the Blackburn game with a hamstring problem and could be unavailable again.
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