Higuain must earn permanent Chelsea deal - Sarri

Higuain sealed a loan move until the end of the season on Wednesday from parent club Juventus having spent a troubled first half of the campaign on loan at AC Milan.

Sarri has fond memories of his one previous season together with Higuain when the striker scored a record 36 Serie A goals in a single campaign.

Now he hopes Higuain can reignite Chelsea's spluttering attack and earn a long-term switch to Stamford Bridge in the process.

"For sure, he is one of the best strikers in my career," said Sarri, who will have to cope without Higuain for Thursday's League Cup semi-final, second leg against Tottenham.

"It's up to him, I think. He has to score, first of all. I think that for a long-term contract, he has to do very well.

"He has to play. He has to score. He has to be useful for the team."

After an excellent start to Sarri's reign in charge, Chelsea have stumbled since losing for the first time under the Italian against Spurs at the end of November.

A run of four defeats in 11 Premier League games has coincided with Sarri's decision to move Eden Hazard into the middle of his front three with the Belgian's impact limited.

Higuain has struggled since being forced out of Juventus in the summer by the arrival of Cristiano Ronaldo, scoring just eight times in 22 appearances for Milan.

Sarri, though, believes he is the best proven goalscorer Chelsea could have added this month.

"Higuain usually is able to score 25 or 30 goals every season," he added.

"As I told you before, in the market in January it's very difficult to secure a very important striker.

"Gonzalo was in a situation that we could try to buy him, and so we decided to try for Higuain."

However, Sarri explained that decision was in part forced by Alvaro Morata's desire to leave Chelsea.

The Spaniard cost a then club record £60 million ($77 million) when he signed from Real Madrid in July 2017, but now seems set for a loan move to Atletico Madrid to make way for Higuain.

"I think that Morata is a very good player. I think that Morata has the characteristics for playing in my team," added Sarri.

"But Morata, one month ago, said he wanted to play in another team. So it was really very difficult for him to give us the 100 percent for his mental situation, I think.

"From the physical and technical point of view, he is a very good player and suitable for my football. But the situation changed in the last month. So we needed to change."