In a body blow for Egypt and their star striker Mohamed Salah, Liverpool's physio has said that the player faced three to four weeks out with the shoulder injury suffered in the UEFA Champions League final.
"He (Salah) is sad about what happened but is totally focused on recovery, seeing when he can be ready," physio Ruben Pons told Marca.
"In principle, it will be between three and four weeks, but we will try to reduce those dates -- that's the big goal."
Speaking after the game, coach Jurgen Klopp described it as a "really serious injury," but the Egyptian Football Federation said it was optimistic that he will be ready for their World Cup opener against Uruguay on June 15.
Egypt takes on hosts Russia, on June 19, and Saudi Arabia, on June 25, in Group A.
Salah has traveled to Spain to undergo treatment, the Egyptian federation said.
The Egyptian star was injured in the 25th minute of Real Madrid's 3-1 win at NSC Olimpiyskiy Stadium after his tangle with the Whites' defender Sergio Ramos, forcing Salah, who has scored 44 goals for Liverpool this season, to leave the pitch in tears, reports Efe.
"Hany Abo Rida (EFA president) has decided to travel to Spain on Wednesday with Egypt's national team doctor Mohamed Abo al-Ela to meet with Salah and Liverpool's medical team," EFA said in a statement released late Monday.
Salah started his rehabilitation programme on Sunday, promising his Egyptian fans he will play at the 2018 FIFA World Cup that kicks off on June 14.
"It was a very tough night, but I'm a fighter. Despite the odds, I'm confident that I'll be in Russia to make you all proud. Your love and support will give me the strength I need," the 25-year-old posted on Twitter.
It was a very tough night, but I'm a fighter. Despite the odds, I'm confident that I'll be in Russia to make you all proud. Your love and support will give me the strength I need. pic.twitter.com/HTfKF4S70e
— Mohamed Salah (@MoSalah) May 27, 2018
Egyptians consider Salah a symbol of national pride and hope after he scored the late winner from a penalty shot during the penultimate game of the 2018 World Cup qualifications against Congo, ending Egypt's 28-year World Cup drought.