Chelsea striker Marc Guiu will be sidelined for weeks after picking up an injury during Monday's 2-1 Premier League win over West Ham United, coach Enzo Maresca said on Friday.
Guiu had replaced Nicolas Jackson, who appeared to pick up a hamstring injury during the first half but played on until the 52nd minute.
"Marc, unfortunately, it's a bad injury," Maresca told reporters ahead of Saturday's trip to Brighton & Hove Albion in the FA Cup fourth round.
"We are still waiting but... it looks (like a) long injury. Exactly how long, I don't know... probably weeks, month, yeah."
Jackson was feeling better but remained a doubt for the weekend, Maresca said.
"We will see, but it doesn't look like a long injury," the coach added.
"Before the last game, we have two strikers, Nico and Marc. Sometimes with also (Christopher Nkunku) there. In case they are both out, we are going to find some different solutions."
Nkunku could play a crucial role for Chelsea going forward after attacker Joao Felix joined AC Milan on loan on Tuesday, Maresca said.
"We were sure before the transfer window that Christo was one of the players we intended to keep," the manager said.
Maresca said letting Felix go was a strategic decision.
"He never complained. He was professional. We need defensive balance and when you have so many attacking players, you can concede transitions and I don't like that," he added.
Chelsea, fourth in the Premier League, visit Brighton again for a league clash next Friday.