The City chief watched as goals from Sergio Aguero, Yaya Toure and a James Milner penalty secured a 3-0 win against Liverpool at the Etihad Stadium on Tuesday evening to move the side three points clear of neighbours Manchester United.
United will move back level on points with a win at Newcastle on Wednesday as the race for the championship crown remains as tight as ever. However, Mancini feels January could be a pivotal month as his side face a hectic schedule without Yaya and his brother Kolo Toure who will jet off to the African Nations Cup after this weekend's FA Cup tie against Manchester United.
"This month without Yaya or Kolo when we play every three days that will be hard," said the Italian.
"January is a very crucial month for us because if we can stay on the top after January we have a big chance to win (the league)."
Mancini, who will also be without Gareth Barry for the FA Cup game after his red card for two bookings against Liverpool, claims Tottenham are also firmly in the race for the title.
"I think United are a strong team but we should think only of trying to win every game if possible and at the end we will see what happens," he added.
"Tottenham are also very close but I hope we stay there (at the top of the table) for a long time."