The Citizens host West Ham in the first leg of the Capital One Cup Semi-Final, but boss Pellegrini has refused to take the struggling London club for granted. West Ham are 19th in the Premier League table, and were beaten 5-0 last weekend by Championship side Nottingham Forest.
But Pellegrini is expecting to face a different side to that who suffered the 5-0 defeat to Forest.
“They had an awful result but I don’t think they played with their best XI, they played with young players,” the Chilean said.
“I am absolutely sure it will be a very different game to what they played on Sunday. We are going to have to have a very good performance to try to win against West Ham.
“It is very important to play the first leg here at home. We will try to win and if we can score more than one goal at home it will be very important also for the second leg.”
Pellegrini is looking to lift his first piece of silverware as City manager, and is likely to field a strong team, despite Premier League matches against Cardiff and Newcastle in between the two legs, as well as a FA Cup replay at home to Blackburn.