Despite a successful loan spell at Juventus, the Chelsea forward failed to hold down a regular first team place at the Santiago Bernabeu.
This allowed Antonio Conte to bring him to Stamford Bridge after the departure of Diego Costa last summer.
But Morata still clearly houses feelings of anger about his Madrid exit.
“I played lots of games but always with the second choice side,” the Blues star revealed in a recent interview with Fiebre Maldini.
“I never asked to be a regular starter, Madrid is another planet.
“But I didn’t play in any of the Champions League knock-out games, or against Barcelona, Atletico, Sevilla and Valencia.”
But now Zidane has hit back, insisting Morata was a key player for Los Blancos during his time in Spain.
“For me there are no small games,” he said ahead of his side’s tie with Espanyol on Tuesday.
“Each one is different, and of course everyone wants to play against PSG before other league teams, but we can’t think about that.
“His role was fundamental in the team, Morata participated a lot and very well in what we won last year.”
Madrid have struggled throughout this campaign.
And lead striker Karim Benzema has only found the net four times in La Liga this term.
Meanwhile, Morata has 12 goals since arriving in west London.