Both Salah and Egypt had said he would be fit in time to feature for the Pharaohs, and he was named to the team's final 23-man roster.
However, while Salah was named to the bench for Egypt's opener, a 1-0 loss to Uruguay, but did not make an appearance in the defeat.
That came after Egypt head coach Hector Cuper had declared Salah a virtual certainty to play, with Cuper then saying after the loss that he did not want to risk Salah in the contest.
Subsequently, the Egyptian Football Association declared Salah had been fit to play and would be available against Russia.
But Salah's fitness remained a question, with Cuper admitting he faced a late fitness test Monday to ensure he was ready for the match Tuesday.
However, Salah appears to have passed that test, as he will start in the right attacking midfield role for Egypt against the hosts.
The forward will make his World Cup debut on the heels of a record-breaking season with Liverpool, in which he scored 44 goals and broke the Premier League scoring record for a 38-game season.
Egypt's hopes for advancing to the knockout stage may well rest on the contest.
After Russia won 5-0 against Saudi Arabia in the opener, the hosts hold a strong goal difference advantage over Egypt, meaning the Pharaohs may well need three points to have a realistic chance at advancing.