Club physio Ruben Pons has estimated Salah would normally need "three to four weeks" to recover from the left shoulder injury he sustained during Saturday's Champions League final against Real Madrid.
Salah, 25, met the national team doctor and Egyptian FA president Hany Abu Rida in Spain on Wednesday.
The forward struck a 95th-minute penalty in the final qualification game to send Egypt to the World Cup for the first time in 28 years.
Despite being Africas most successful nation, in two attempts, Egypt haven't won a single World Cup match.
President Trump, Kim Jong Un summit needs a plan
Once he sees that Trump is willing to bully the Chinese a little bit, then I think Kim will actually start to play ball with us. Before canceling the summit last week, Trump said that China had eased up enforcement of sanctions on its border.
"I've taken the decision to not continue next year as Real Madrid coach", he confirmed at a press conference called by the club.
Salah was hacked down by Real Madrid defender Sergio Ramos in the first half of the Champions League final in Kiev. "Despite the odds, I am confident that I will be in Russian Federation to make you all proud", he wrote on Sunday.
Shorn of their star man Liverpool went on to lose 3-1.