The Belgian forward scored a goal in either half to lead the Blues to a 2-0 win over the Hammers at Stamford Bridge.
The first of his brace was a stunning effort as he slalomed through four West Ham defenders on the edge of the box before slamming his shot into the bottom corner.
Hazard now has 15 goals and 12 assists in the Premier League, having contributed to just shy of 50 per-cent of Chelsea’s top-flight goals.
The 27-year-old’s future in west London is however uncertain with Hazard strongly tipped to join Real Madrid this summer.
The winger has not-so-subtly flirted with a Bernabeu switch since the World Cup last summer and is out of contract with Chelsea in less than 18 months.
Recent reports have indicated Real Madrid are increasingly confident of landing Hazard, though Chelsea want to recoup around £100m despite his contractual situation.
And asked about that price tag after Hazard’s West Ham double, Sarri admitted: “It’s too cheap in this market. It’s too cheap.“
Worryingly, however, the Italian coach conceded that he can do little to stand in the way of Hazard if he believes now is the right time to end his seven-year stay at Chelsea.
Quizzed as to whether the club can afford to lose their talisman, Sarri added: “We are trying to improve. We are trying to become one of the best teams in England and in Europe.
“From the technical point of view, no. Not at the moment.
“Also, because it’s impossible to find another Hazard. At the moment there isn’t another Hazard, the level is so high.
“You’d have to find two players to make the level of Hazard. So I hope Hazard can stay here, otherwise we’ll have to try something different.
“I’m sure the club doesn’t want to sell him. But, of course, we all have to respect his decision.
“He’s in the last season of contract [next year]. If he wants to have another experience, we’ll respect that.
“We’ll try, of course, in any way to convince him to stay, but it’s not easy.”
Hazard insisted his future is not yet decided when asked about links to Madrid after West Ham fans taunted Chelsea about an apparently imminent move to the La Liga heavyweights.
He told Sky Sports: “Nah, they are wrong. Now I am just focused with Chelsea till the end of the season. I just want to finish in top four, [win the] Europa League.
“We still have a lot to do. Then we will see.”