Nkunku suffered the blow during a pre-season friendly against Borussia Dortmund in Chicago.

"We are working in the market because we are going to miss an offensive player like this," said Pochettino.

"The club is working, trying to find a solution for maybe short term, medium and long term to add the right profile for the team to perform from now."

Nkunku, who completed a £52m move from RB Leipzig to Chelsea in the summer, impressed during pre-season with three goals in five games before his injury.

"We feel very sorry about him. He was doing well, he is very important for us," Pochettino said.

"Now it's about not thinking too much about the injuries and to be positive about when he can be back with us."

Chelsea open their Premier League campaign when they host Liverpool on Sunday (16:30 BST) following a summer of upheaval in which Pochettino took over as the club's manager.

A number of players have left the Blues, including Kai Havertz, N'Golo Kante, Kalidou Koulibaly, Mateo Kovacic, Edouard Mendy, Mason Mount and Christian Pulisic.

Meanwhile, Nicolas Jackson, Lesley Ugochukwu, Angelo Gabriel, Diego Moreira, Robert Sanchez and Axel Disasi have joined the team who finished 12th in the Premier League last season.

"Of course, we are Chelsea. The history of the club is to win. Even if we are in transition, we need to win and be ready to win against Liverpool," said Pochettino.

"The mentality for the players is to compete and try to win. I'm not going to accept a different way to think. We want to put the club where the club deserves to be."