The Premier League Golden Boot winner will abstain from eating and drinking during daylight hours during the month of Ramadan which started on May 16.
According to Egyptian publication Al Masry, the Red forward insisted he won't break his fast despite the magnitude of the upcoming fixture against the 12-time European champions - and it won't affect his display in Kiev.
However, nutritionist Jesus Munoz refuted the claims made by the Liverpool Player of the Year.
"Even though they feel cleaner, they are less prepared for physical exercise," he said, as quoted by Marca. "If he (Salah) perfectly fulfils Ramadan, his performance will be affected."