Morata has struggled in front of goal in recent months, but he struck a brace to maintain Chelsea's excellent start to the season and take his personal tally to four goals in his last four Premier League games.
Speaking to 'Sky Sports' after the game, Sarri was full of praise for the Spaniard, saying that he has the potential to improve yet further in the weeks and months ahead.
"He improves in confidence, in personality, in playing with the team, so now I am very happy," the Italian enthused.
"He can improve more because the technical potential and physical potential is great, now he has confidence he can improve more."
The hosts suffered a brief scare just after the break as Andros Townsend drew Chelsea level, but Hazard laid on Morata's second within two minutes of coming off the bench to put his side in the driving seat once again, much to Sarri's delight.
"In that moment we needed Hazard," Sarri admitted. "After the goal at 1-1 we were in a little bit of trouble so we needed accelerations, assistance, and Hazard got the assist in a minute.
"As I said before it was very important to have him on the bench."