Shakhtar Donetsk chief Darijo Srna insists Mykhaylho Mudryk will come good for Chelsea.
The Ukraine international is yet to register a goal or assist in a Chelsea shirt as Graham Potter struggles to settle his side after a frantic transfer window.
Despite their troubles, Srna, who was instrumental in the deal to bring Mudryk to the Premier League, says he can still bring a lot of joy to Chelsea fans.
Speaking to the Football Ramble, he said: Don't worry about Mykhaylo Mudryk, you will enjoy watching him. His first game against Liverpool, this is 35 per cent of Mudryk, believe me.
"Chelsea is not in a good mood, they are not playing amazing football and don't have good results but they have a lot of players and need time.
"Mykhaylo will be okay, don't worry. Mykhaylo will bring a lot of happiness to Chelsea fans.
"Chelsea now is not in a good mood and Mykhaylo as well but Mykhaylo has all the quality to be one of the best players in the Premier League in the next two years.
"Mudryk is one of the best three players in his position in Europe.
"After Kylian Mbappe and Vinicius Jr it is Mudryk."
Srna added: "Regarding the transfer proposal, the price was 100million (88m), 70million plus 30million.
"Arsenal were in love with Mudryk, but Chelsea were more concrete and were more ready to buy him.
"With respect to Arsenal, in the end it was the decision of Mudryk because Chelsea paid what we wanted and we made an agreement with Chelsea he said he wants to go to Chelsea, it's simple."