And the Italian sees similarities in Morata, who has struggled for consistency, despite having scored five league goals this season.
"Saponara was one of the best players I have ever seen, but a little bit mentally fragile.
"Alvaro has scored four or five goals in his last six matches, so I cannot see a big problem. I hope that there will be more this season.
"Every season he scores 15 or 16 goals, so he's around his average [goal return]. I speak with him every week, but on the pitch he is alone.
"I think that at the moment he's not playing to his full potential. It's difficult."
This is the second time in recent months that Sarri has questioned the mental strength of Morata, who is battling Olivier Giroud for a place in the Blues starting XI.
He said: "I think Alvaro has a very great physical and technical potential, so I think he can improve more.
"He's a little bit fragile from the mental point of view. But he's very young. I think he can improve, improve very fast."