Chelsea boss Sarri took over from Benitez at Napoli in 2015 and led them to second place behind champions Juventus last season.
It was that success which led Chelsea to turn to the 59-year-old Italian to replace Antonio Conte this summer.
But Sarri insists it was his predecessor who laid the foundations, and he will get the chance to show his appreciation when the Blues travel to Benitez’s Newcastle on Sunday.
“I have to say thank you to Rafa because when I arrived in Naples I had a feeling the team was almost ready to play my football,” he said.
“If I arrived after another coach maybe for me it was more difficult, so I have to say thank you to him.
“I know he is a very good coach. We know on Sunday it will be very difficult for us.
“These opponents are very dangerous for us; last season we lost 3-0, Manchester United lost there, Arsenal lost there, so we know it will be a very difficult day.”
Sarri’s Napoli pushed Juventus all the way in Serie A last season.
Sarri is a heavy smoker but there is also another habit he cannot give up – his four-man defence.
Chelsea certainly looked defensively frail at times during the 3-2 win over Arsenal last weekend.
Yet although Conte led Chelsea to the title in 2017 after switching to five at the back, Sarri will not be following suit.
“Have we worked on defence this week? Every week,” he said.
“I am not worried about the defence. When I arrive in a new team usually I have problems with the defensive base for two months, so it’s not a problem.
“I am not able to play with five defenders. We are trying to defend by looking only at the ball and if I defend with five defenders I lose metres on the pitch.
“I’m not able. I tried it five years ago, but it’s not my way.”
