But Sarri says he may need increase that number as the season goes on.
He said: "I don't know because for an English team the Europa League is a very difficult competition, because in Italy, if I play in Greece on Thursday I can ask to play on Monday night, but I have to play again in 63 hours, on Sunday morning. I don't know in the future.
"It is not a big problem now because we have played only six matches but in the future it may be a problem. I hope to qualify before the last one or two matches of the group stage."