Having earlier this month become the first side to win at Manchester City this season, the Portuguese insisted his side were not serious contenders for the Barclays Premier League title.
Mourinho called his side a "little horse" in comparison to fellow title challengers Arsenal and City, whose manager Manuel Pellegrini quickly hit back at such talk.
The man he succeeded at the Etihad Stadium echoed those thoughts today, with Mancini, now manager of Galatasaray, insisting Chelsea's class and experience makes his team huge underdogs for the last-16 clash.
"It's a young team, like ours," the Italian said with a smile
"We are young.
"I think that Chelsea are on top of the Premier League because they are a top team.
"They have really good players - these players who can change the game at any moment.
"They have fantastic players who are used to playing games like this
I think they have an 80 per cent chance of going through."
Mancini believes a positive result is required on Wednesday if the Turkish champions are to stand any chance of progressing to the quarter-finals.
Galatasaray's attack is expected to be their biggest strength in the last-16 tie, with two men Mourinho knows well key to that.
Wesley Sneijder won the Champions League under the Portuguese at Inter Milan, while the match will be Didier Drogba's first against Chelsea since ending his time with the club as a European champion.
"Didier was an important man, an important player for Chelsea," Mancini said
"Wesley won under Mourinho a Champions League.
"They have a good relationship with him, but tomorrow, for 90 minutes, I think they will be enemies.
"Ninety minutes, afterwards, they can go and have a dinner together
But for 90 minutes they should not play 100 per cent, but more
We need Didier and Wesley to play very, very well tomorrow."
Both players should need little motivation for the match in Istanbul and the same goes for Mancini.
The Italian was succeeded at the Inter Milan helm by Mourinho and this is his first match against English opposition since being sacked by City.
Mancini has fond memories of his title-winning time at the Etihad Stadium despite the unceremonious manner of his departure, but was coy when asked about a return to the Premier League.
"Now I am here and very happy, feeling very good in Istanbul," he said
"Galatasaray are the best team in Turkey and I'm happy with my job.
"I did a good job in Manchester, in my opinion, and I am very happy with what we did, very proud.
"In football it's impossible to know the future because this can change in every moment.
"I don't know if I can come back to work in the Premier League, or if I will work in another country or stay here another five years
I don't know
But I'm proud with what I did at Manchester."
Source : PA
Source: PA