Mohamed Salah (Getty Images)
"The football federation reiterates that Salah will be at the World Cup, God willing, and will be out for no longer than three weeks," the federation said after its president Hani Abu Reda and the team doctor met with Salah in Spain, where he is undergoing treatment.
A full three-week absence would likely keep Salah out of action until at least June 17, meaning he would miss Egypt's opening fixture in Group A against Uruguay on June 15.
They then face Russia on June 19 and Saudi Arabia on June 25.
Salah arrived for rehabilitation in Valencia on Sunday, the day after he injured his shoulder after being wrestled to the ground by Sergio Ramos in the Champions League final Real Madrid won 3-1.
The Egyptian FA announced on Monday that their star player, who hit a stunning 44 goals for Liverpool last season in all competitions, had started rehabilitation immediately on Sunday in the hope of playing a role in Egypt's first appearance in the World Cup since 1990.