Mohamed Salah was rested for Friday's loss to Uruguay in order to be fresh for Egypt's final two Group A matches, admitted manager Hector Cuper.
The Liverpool ace watched from the substitutes bench as Jose Gimenez pinched a late winner for Uruguay.
"Perhaps if Mo had been on the pitch today, the outcome would have been different but we can't know that," Cuper told reporters after the game.
"At the end of the training session we examined him and there was some doubt if he fell or was hit by another player, and we wanted to avoid a risk today," Cuper said. "We want to have him in top form for Russia and Saudi Arabia."
Salah will be tasked with leading his country in a must-win match against Russia in Saint Petersburg. Egypt's final game is against Saudi Arabia.