Cech took part in training on the eve of the contest a week after being ruled out for the season by Mourinho with a dislocated shoulder sustained in the first leg.
Cech departed after 20 minutes of last Tuesday's first leg, which finished 0-0, to be replaced by Mark Schwarzer, who is poised to continue in the second leg.
Mourinho insisted the Czech goalkeeper trained alongside injured personnel, suspended players and those fully fit to show solidarity.
"Everybody's ready and he's ready and that's the message we wanted to give," the Portuguese said
"Everybody was on the pitch.
"It's a very important match for our group
Everybody's together, everybody wants to help, everybody wants to play.
"His condition doesn't allow him to play, but the message from him and the group."
Captain John Terry (ankle) was also present in training, having initially been ruled out up to the May 24 final in Lisbon, while Eden Hazard (calf) and Samuel Eto'o (knee) were also present after recent absences.
As well as playing for a place in the Champions League final and a third European final in three years, the Blues are in contention for domestic silverware
The London side won 2-0 at Liverpool last weekend to keep themselves in with a chance of the Premier League title, albeit a slim one with two games to play.
Mourinho's defensive tactics were criticised, among them by Liverpool boss Brendan Rodgers, who accused Chelsea of "parking two buses".
"Pundits are pundits and I don't want to comment a lot," added Mourinho, who employed Rodgers at Chelsea during his first spell.
"Brendan is a manager and is somebody that I consider my friend.
"I met him a long time ago when he was a very young coach coaching kids and I consider him a friend.
"I know his words after the match but I also know his words today and today he told me congratulations for a great victory and a great performance.
"I prefer to forget the words after the match and I keep the words of today."
Mourinho confirmed Terry, who was sitting to his right at the pre-match media conference at Stamford Bridge, will start against Atletico and believes his skipper deserves more from the Champions League after a challenging history
Terry missed the decisive penalty in the 2008 final loss to Manchester United in Moscow, was absent for the 2012 win in Munich through suspension and was injured for last season's Europa League final win in Amsterdam.
"I think he deserves more than the Champions League gives to him till now," Mourinho said.
"He lost a few semi-finals in special circumstances, he lost the final also in special circumstances.
"He won a final, also in special circumstances, because he couldn't play the final
I think Champions League owes him something.
"My captain is playing at the same level as when I left Chelsea in 2007/08.
"Six or seven years later he is playing at his best level
It's fair to say that.
"It's also fair to say that the people that surround him are playing also fantastic
"I think his partnership with (Gary) Cahill is fantastic and people that work together in the same areas - they are doing a fantastic job.
"I'm really happy to see a player like him, six or seven years later to be back to the same level."
Source : PA
Source: PA