The Italy playmaker followed Sarri from Napoli to Stamford Bridge last summer in a £57m move. He is a key component of the possession-based 'Sarri-ball' philosophy which has been turgid at times this season.
Jorginho was booed by Chelsea fans when going on as a substitute in the recent win over Malmo and missed a penalty in the Carabao Cup final shootout loss to Manchester City.
But Sarri expects the 27-year-old to improve as the team learn "our way of football".
"Jorginho has a very strong character, a very strong personality," the 60-year-old Blues head coach said.
"So I can believe that he has no problem to play under pressure. I think that he played very well in the last match (against Tottenham), better in the second half than in the first half.
"For him, it's very important to finish the match in that way.
"I think that he can do better. But he needs all the team to understand very well our way of football."
It is Sarri who has been under examination of late, with heavy defeats at Bournemouth and Manchester City and the negative reaction of fans to the FA Cup exit to Manchester United rendering his position precarious.
That was before the Kepa Arrizabalaga substitution furore when the world's most expensive goalkeeper refused to go off at Wembley with penalties looming.
City won the shootout 4-3 and debate raged at whether Sarri's position had been undermined.
The situation appears to have galvanised Chelsea, while it was Sunday's opponents who made a managerial change.
Claudio Ranieri was sacked and former Blues midfielder Scott Parker will take charge of the home side at Craven Cottage.
Sarri says the only pressure which bothers him is internal and he had the same drive when he was working as a banker while managing amateur football teams in Italy.
"My pressure was the same," Sarri added.
"The pressure is inside. I felt big pressure in Serie C, and very little sometimes in the Champions League. It's really very important your feeling at the moment."
Sarri repeated his oft-uttered view that the pressure was greater at Napoli, where the supporters are renowned for their passion than in his present position at Chelsea.
"Napoli is not a small club. And the pressure is a lot higher there than here," he said.
Sarri hopes the Blues' midweek defeat of Tottenham can see Spurs slip back to make it a four-way battle for two Champions League qualifying spots, with Arsenal and Manchester United also in contention.
Chelsea are trailing the trio, albeit with a game in hand, and Sarri knows the Blues cannot afford to take any opponent lightly.
He added: "Every match is very difficult and mentally very expensive. You risk arriving at this moment of the season really very tired, more mentally than physically. In England, the season is really very difficult.
"The target of my club is to return in the Champions League. I would be really very happy."
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