Links with a move to Real Madrid for the Belgium global have persisted, with the winger recently refusing to be drawn on whether he would commit long term to Chelsea and extend a contract that expires at the end of next season.
"Against Leicester I think we played one of the best performances of the season in the first half; what was wrong was the reaction to the negative situation, but it can happen", said Sarri.
Madrid are long-time admirers of Hazard, and speculation linking the Belgian with a move to the Spanish capital has only intensified as his contract ticks down.
Chelsea are yet to enter into negotiations with Hazard's camp regarding a new deal and Sarri says the time has come for the club to be decisive.
"But, like today, I did well as a striker like against Brighton".
"I can not see a problem of Hazard in this role".
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Also, Koulibaly was suspended for two matches - one for the red card and one for applauding the referee. Koulibaly's compatriot and Senegal teammate Sadio Mane has now sent a message to the centre-back.
Hazard is not the only high-profile player at Chelsea with an uncertain future.
So Sarri's debut season has included positives.
'The second problem was Odoi, it's not a serious problem but I don't think he will play in the next match'.
'It is good not just to be a target man, but also as a false nine where I can move, I can drop, I can go deep, I can go on the wing.
"We have two problems". "The policy of the club is only to renew for one year for players over 30 years old".
Asked if he thinks Hazard has already made a decision, Merson said: "I would say yes".