Egypt earned themselves a penalty 20 minutes from time after Salah was hacked down, with the Liverpool striker picking himself up before smashing the ball into the net to reduce the deficit.
The shoulder injury he suffered at the hands of Sergio Ramos kept Salah out of Egypt's unfortunate 1-0 defeat to Uruguay, and he was clearly rusty in St Petersburg.
The first was an own-goal by Egypt captain Ahmed Fathi - a veteran with 129 global appearances - after the ball came back in following a botched clearance.
Cheryshev came off the bench to score twice as Russian Federation thrashed Saudi Arabia 5-0 in the tournament's first game last week.
The defeat stunned Egypt, a soccer insane nation of some 100 million people whose hopes have been pinned on Salah delivering the desired result.
"The World Cup is not awarded to the team that scores eight goals first", Cherchesov told reporters after the match.
Diego Costa's fluke goal edges Spain past Iran, closer to knockout rounds
Iran , though, did not lie down as other teams have done in this World Cup , instead laying into Spain with everything they had. David Silva sent a free kick straight into the arms of keeper Ali Beiranvand in the 25th minute for Spain's first shot on goal.
Following the result, reports surfaced that the country's showing in their first two games had caused conflict between the players, staff and the fans watching at home. They shouted every time Salah's face flashed up on the big screen and when his name was announced before kickoff. He didn't touch the ball until the seventh minute. He converted it in the 73rd minute, but it wasn't enough.
Salah's injury denied Egypt having their star man on top form at the showpiece event, according to coach Hector Cuper.
Cheryshev, who entered the World Cup as a fringe player, is proving lethal in front of goal, with his latest a side-footed effort from close range from Mario Fernandes' cross in the 59th.
"With the ball, without the ball, he can dribble, he can attack spaces behind defenders".
Much now depends on the Uruguay-Saudi Arabia game on Wednesday in Rostov. It was also his third goal of the campaign.
However, Russia had enjoyed a far more positive start in thrashing Saudi Arabia 5-0 to snap a seven-game run without a win heading into the tournament and their greater confidence showed early on.