Gonzalo Higuain has admitted to Chelsea boss Maurizio Sarri that he has struggled to adapt to the Premier League.
Striker Higuain retired from international duty on Thursday, bringing down the curtain on an Argentina career comprising 31 goals in 75 caps, an appearance in the 2014 World Cup final and Copa America finals in 2015 and 2016.
The 31-year-old joined Chelsea on loan from Juventus in January, scoring three goals in seven Premier League appearances.
Now Chelsea boss Sarri has called on Higuain to hit top form to spearhead the Blues' final Premier League top-four tilt, starting at Cardiff on Sunday.
"He said to me that it's difficult, because the physical impact of the defenders here is really very strong," said Sarri.
"The referees here are really very different than in Italy, and so it's another football for him, especially for a striker and a goalkeeper, it's really very different.
"And so I think that he needs time, but we have no time. So we need him at his top level in the last two months."
Chelsea striker Gonzalo Higuain has announced his retirement from international football with Argentina, citing family reasons.
The 31-year-old, who joined Chelsea in January on a loan deal from Juventus, scored 31 goals in 75 appearances for the Albiceleste, with his last match a 2-1 win over Nigeria in the World Cup last June.
Explaining his decision in an interview with Fox Sports, Higuain said: "My time with Argentina is over. Thinking things through in depth, my time is up.
"To the delight of many, now I will only look at it from the outside. I have spoken to (manager Lionel) Scaloni and told him my point of view.
"I've made the decision because I want to enjoy my family, I want to spend time with my daughter, and at the same time, I feel that I gave my country everything I could."
Higuain, who has scored three goals in 10 appearances since joining Chelsea towards the end of January, added: "I'm fully focused on my commitment to Chelsea.
"The Premier League is amazing and I really want to enjoy it. It's very competitive indeed."
Gonzalo Higuain has been backed to hit the ground running with Chelsea.
The 31-year-old striker completed his loan move from Juventus on Thursday and could make his debut in Sunday's FA Cup fourth-round clash with Sheffield Wednesday at Stamford Bridge.
Chelsea assistant boss Gianfranco Zola said on Friday: "We're talking about a player who has scored not only in Italy but everywhere, also in the Champions League.
"I'm sure he can handle expectations. He's always produced good numbers wherever he's been. We're going to help Higuain to get his goals."
A decision is yet to be made on whether Higuain will feature.
Zola added: "There are players who need to be rested and it could be an opportunity."