The Belgian winger was brought on for Pedro after an hour with the game tied 0-0.
It took Chelsea until the 86th minute to break the deadlock, as Marcos Alonso struck just minutes from time.
Hazard had a solid
And speaking after the game, Sarri admitted that he did not plan to play Hazard at all.
“No, at the beginning of the match I wanted him on the bench because I thought that, probably, the match was really very difficult.
“[If the match was difficult] Probably I’d need to use him. Of course, if at the end of the first half we were [winning] 1-0, I wouldn’t have used him.”
Despite it taking until the final moments of the game for Chelsea to find a breakthrough, Sarri insisted he was happy with his side’s performance.
The Blues will welcome Slavia to Stamford Bridge next Thursday, and the Italian coach believes the return leg will be much tougher.
“It’s very difficult to face them,” he said. “Really very difficult.
“I’m really happy with the result. Also with the performance because, in this moment, we are able to suffer.
“In the past we were not able to suffer in the difficult moments of the match.
“We need to think that the second leg will be difficult because these opponents are really very dangerous also away. Like in the round against Genk.
“And so we need to be careful. It’s very difficult to face them. Really very difficult.
“I’m really happy with the result. Also with the performance because, in this moment, we are able to suffer.
“In the past we were not able to suffer in the difficult moments of the match.”