The Argentine, 31, has been released from his loan to AC Milan, where he has scored eight goals in 22 games.

Higuain did not sign before Wednesday's midday deadline and cannot play in Thursday's Carabao Cup semi-final second leg against Tottenham.

"We hope he [Higuain] can get back to his best form," said Sarri.

Higuain was linked with Arsenal when Juventus signed him for a then domestic record £75.3m in July 2016.

After scoring 40 league goals in two seasons, he moved to Milan in August, with the option of making the deal permanent at the end of the season for a fee of 36m euros.

His spell at Milan began well, with six goals in five games, but he has only found the net once in his past 12 appearances and was left out of Monday's match with Genoa after Milan coach Gennaro Gattuso said: "Speculation disrupted preparations."

In 2015-16, at Napoli under Sarri, Higuain equalled the Serie A goalscoring record with 36 goals.

"He is a very strong striker, especially in my first season at Naples," said Sarri. "He did very very well, for sure he is one of the best strikers in my career.

"Higuain is a few hours away from signing his contract with Chelsea. I hope that he will start scoring for us. I know he has had some difficulties at the moment."

Chelsea are currently fourth in the Premier League, three points ahead of Arsenal who beat them 2-0 at Emirates Stadium on Saturday.