The reigning Spanish champions are set to resume UEFA Champions League duty in their round of 16 first leg clash with Manchester City at the Etihad Stadium later on Tuesday.
Mourinho has had a chequered history with the Camp Nou outfit following his tenure as manager of Real Madrid.
The Portuguese has also been involved in a back-and-forth of sorts with City manager Manuel Pellegrini, though the Chilean saw his team come out on top when City beat Chelsea 2-0 in the FA Cup on Saturday.
Mourinho believes that Gerardo Martino's men will start as favourites to progress to the quarter-finals of the Champions League, but that City should be confident against a Barca side that he feels is not as strong as in previous seasons.
"Of course, by history, Barcelona is the favourite, but this Barcelona, this season, is showing that it is not the same in previous years," he said in an interview with ITV.
"Of course they have (Lionel) Messi, he is special, and they have more than him. But I think this is the worst Barcelona of many, many years - so City have a chance."
Meanwhile, Ashley Cole's future at Stamford Bridge remains in doubt after Mourinho failed to guarantee the full-back playing time ahead of the FIFA World Cup in Brazil later this year.
Cole is hoping to start as Roy Hodgson's first-choice left-back for England, but he has lost his starting berth at Chelsea to Spaniard Cesar Azpilicueta.
"I don't know (if Cole will get a run in the first-team)," Mourinho continued. "I'm very happy with the way Azpilicueta is performing.
"I cannot think (about) national teams at the same time as thinking about my team.
"There are national team managers that are very clear: they go with their players. It doesn't matter if their players are playing in the club, (if) they are not playing, they go with their players."
