The Blues legend believes the Spaniard is “going in the right direction” having scored three goals in his first four Premier League games but, having expressed doubts about his suitability to fill Costa’s shoes in the summer, he insists Morata still has plenty to prove.
Speaking on the Alan Brazil Sports Breakfast, the former Italy international said: “I know he is a very talented player with amazing skills, but he has never been a regular.
“He played with Juventus and he wasn’t a regular, the same for Real Madrid. Nobody doubts his qualities but he is still young and needs to find consistency because when you play for teams like Juventus, Real Madrid and Chelsea you have to be consistent.
“Obviously Antonio Conte with his methods, his work ethic, he is helping him a lot and it seems he is going in the right direction.
“For Chelsea, the main striker is a vital position and if he plays well then Hazard, Pedro, Willian, all the players around him, will play well also.”
While Morata is making his mark at Chelsea, the man whose spot he has taken remains in limbo.
Costa is currently AWOL in Brazil and refusing to return to the club after being told by boss Conte in the summer – allegedly via text message – that he is no longer wanted.
Zola admits the Spain international is a ”big loss” to the Premier League champions, but says there must be a good reason for Conte to want the striker out.
“Nobody doubts the quality and value of the player but something must have gone wrong in the changing room,” he said.
“A manager who is day in, day out in the changing knows how important a player is, not only on the pitch but also within the group, so if Conte has come to this decision it means probably there were no guarantees any more to have that harmony in the changing room.
“It is big loss for the club because we know how important a player like Diego can be but you have to pay respect to the manager, who has to look after 24 players not only one.”