Mancini always knew he would be in for a tough month, with the Toure brothers away on international duty and a run of tricky fixtures.
Vincent Kompany and Mario Balotelli were also hit with four-match suspensions and David Silva picked up an injury as City crashed out of the Carling Cup and FA Cup.
They also suffered Premier League defeats against Sunderland and Everton, before Saturday's victory over Fulham re-established a two-point lead in the title race as Manchester United drew with Chelsea.
Mancini will soon have all his key players available again and he feels City are still on course to become champions.
"It is important to be at the top at the moment - this is very important," he said in the Daily Star.
"During the season we know there are difficult moments. I don't think we had a bad month in January, but we had a difficult month because this can happen with injuries, players away and players banned.
"If you have these problems, maybe it's clear that you can't always play very well."
Mancini insists that City will not pay much attention to how their rivals are performing during the run-in and will focus on their own results, starting with a trip to Aston Villa on Sunday.
"We will have a difficult game in Birmingham but if we have the same attitude that we had on Saturday against Fulham we will do well," said the Italian.
"It is important that we stay top and don't think about the other teams."
He added: "Manchester United can win all their games - they are strong like us. For this reason I don't think we can think about the other teams."