Cameroon striker Samuel Eto'o missed training for the second consecutive day on Sunday, and the ex-Chelsea hitman is a major doubt for the African side's crucial match against Croatia.
Coach Volker Finke will need as many fresh legs as possible for the Group A battle, which will take place in the sweltering heat and humidity of Manaus on Wednesday.
But he may be without his talisman up front, making Cameroon's task to qualify for the knockout stages even tougher than it already is.
The Indomitable Lions lost their World Cup opener against Mexico 1-0 on Friday and will need to pick up four points from their remaining to games against Brazil and Croatia to get out of Group A. That is a daunting challenge even with Eto'o, and a seemingly impossible one without him.
Finke confirmed the striker's injury. He said: "He has a problem with the right knee that he already had at the end of the season with his club Chelsea. He did not train yesterday nor today."
After a club season where his age was questioned by Chelsea boss Jose Mourinho, who asked "he is 32 years old, maybe 35, who knows?", this tournament is perhaps Eto'o's final chance to shine on the international stage.
However, his performances are in noticeable decline, and with their qualification chances looking slim it may be a good opportunity for Finke to give some of his younger players some World Cup experience.
Lorient's Vincent Aboubakar and Malaga's Fabrice Olinga are potential candidates to step into a forward role in Eto'o's absence.