City are on a good run of form going into the match at Upton Park and are looking to stretch their unbeaten streak to seven Barclays Premier League matches.
Mancini remains wary of the Hammers, though, and said: "This championship is very good because every game is difficult. If you think you have an easy one it is a disaster."
The absence of suspended captain - and former West Ham striker - Carlos Tevez will make City's task even harder but Mancini is expecting another big performance from summer signing Yaya Toure.
"I always thought he was a fantastic player," said the Italian. "He can play in different positions. He has experience, technique and strength, everything."