Egypt confirmed Salah's inclusion in the line-up minutes after an earlier tweet was published with a list omitting the star striker's name. Salah, 26, was later seen warming up in the Volgograd Arena with his teammates.
His presence had been the subject of speculation following media reports the talismanic player was on the verge of quitting international football after unwittingly becoming a publicity pawn for the Kremlin-backed leader of Chechnya, Ramzan Kadyrov.
The Egyptian Football Association denied reports earlier in the day about Salah, who has been recovering from a shoulder injury.
Egypt also gave 45 year-old keeper Essam El-Hadary a chance to become the oldest ever player to appear at a World Cup.
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Both Egypt and Saudi Arabia lost their first two games and will be hoping to pocket an elusive win in Volgograd to avoid finishing bottom of the group.
Saudi Arabia fielded Yasser Al-Mosailem as goalkeeper, meaning that the kingdom's three keepers will each have played one game in Russia.
(Reporting by Alexandra Ulmer; Additional reporting by Osama Khairy; Editing by Hugh Lawson)
