City and Arsenal face Barcelona and Bayern Munich this week needing to overturn 2-0 goal home deficits to progress to the Champions League quarter-finals.
Should they exit Europe's elite competition, then their energies can be channelled towards a Premier League title race which Chelsea lead by seven points, albeit having played more games than their rivals.
Mourinho said: "Can't City win in Barcelona? Barcelona lost against Valladolid. And lost at home against Valencia. So, why can't they win?
"Arsenal, at Bayern, can they win 2-0 and go to extra-time? Difficult. Probably the most difficult, but they can."
Mourinho also believes Chelsea's progress is not a formality after a 1-1 first-leg draw at Galatasaray. The second leg is on March 18.
"Our result is very dangerous," he said.
Chelsea, having played a game more, are seven points clear of Arsenal and Liverpool, who are not in European action this season, while Mourinho's favourites City are nine points adrift with three games in-hand and a far superior goal difference.
"When we speak about Champions League and the title race we have to speak about Liverpool," Mourinho added.
"Since the beginning of the season they have one match every week. They rest, they prepare, they recover, they prepare, they play, they have day off. This is a big, big, big advantage."
Former Liverpool striker Fernando Torres faces a wait to discover the full extent of the groin injury which forced his withdrawal following the warm-up prior to Saturday's 4-0 defeat of Tottenham.
Mourinho said: "It's a muscular problem and muscular problems, even when they are small are always a couple of weeks.
"I don't know if it's small or big. He has to go for scans, but for sure he's out."
Samuel Eto'o stepped in and scored the opening goal after an error by Jan Vertonghen.
Mourinho praised Eto'o for being in the right place at the right time, as the Cameroon striker has been often this season, even if his goal tally has not amounted to as much as Chelsea might have hoped.
"He's obviously very intelligent in the way he moves," Mourinho said.
"He read Vertonghen's mistake. Fox goals."
Eto'o was adjudged to have been fouled by Younes Kaboul, who was sent off, for a penalty which was converted by Eden Hazard.
It appeared harsh and Mourinho will look at the incident, but insisted there are no divers at Chelsea.
"You know the kings of the penalties, you know where they are and they are not here," he said.
The injury to Torres may grant Demba Ba, who scored a late double, an opportunity for a first Premier League start since October. Ba came close to leaving last summer.
Mourinho added: "It's one of the best decisions we made, to keep three strikers.
"When one is injured you need the other two."