Terry has rejected a surprise move to Spartak Moscow for family reasons after leaving Aston Villa following a single season with the Championship club.
Terry previously indicated he wants to return to Chelsea as the club's manager and Sarri has opened the door for the 37-year-old to join his coaching staff.
"I'm very happy for him", he said of Ampadu. I think so, but I hope not.
Liverpool now top the table with four wins out of four, though Chelsea and Watford are also on 12 points after their ideal starts to the season.
Hazard's hat-trick boosted his tally to five goals in as many Premier League appearances and kept him on track to beat the 23 he netted in all competitions in his final season at Lille.
The Premier League clash kicks off at 3pm at Stamford Bridge.
"In a few days, one week, he will be ready to play".
"My target is to be the best team in England, but not in one month - maybe one season, maybe a little more". At the moment he is able to be on the bench.
"If there is a pitch and there are 11 players, I feel at home anywhere", Sarri said. "It will be a very hard game for everybody who plays Cardiff".
Sarri was pleased with his side's efforts against the winless Bluebirds but said reiterated that they were still "a step away" from Liverpool and Manchester City.
Ampadu made headlines with his composed performances at senior level for Wales during the global break, and Sarri said that he hopes to find minutes for the 18-year-old as well as Chelsea's other talented youngsters on the fringes of the first-team squad as the season wears on.
"My feeling is that now we are not a very solid team in the defensive phase". I think so. When he gets the ball, he can hold it and we can go with him.