City beat Southampton 4-1 today to move within a point of Liverpool, with one game in hand.
The Chilean believes that there is still a lot of football to be played, regardless of next week's result.
"Now we have an important game against Liverpool," Pellegrini told BT Sport.
"We have a lot of time to prepare during the week so it is an important game but I don't think it will decide the Premier League.
"After that, we have to play six games and Liverpool have to play four games more."
Liverpool can increase the gap again with victory over West Ham United tomorrow.