Celtic are due to take on Zenit. St Petersburg in the Europa League on Thursday.
Celtic have been back in action for weeks now, following the winter break, and they are back to full sharpness.
However, Zenit come into the game on the back of a lengthy winter break.
The Russian side have not played in a competitive game in the whole of 2018.
And Mancini admits that Celtic are in an advantageous position heading into the contest.
“Our biggest problem could be that we haven’t played a competitive match in a long time," Mancini said. "Our last game was two months ago and that’s a long time to wait.
“Will this be an advantage to Celtic? Well it’s certainly a disadvantage for us. But we will have to deal with the problem if we hope to go further in the competition.”
Celtic are desperate to progress in European competition, and Brendan Rodgers has made no secret of his desire to take the Europa League seriously.
Celtic already look to have the Scottish Premiership title wrapped up, so their match against Zenit is hugely important.
Celtic made it into the Europa League knockout stages by finishing in third place in the Champions League group.