Murphy is sure the Egyptian will exploit any void left in Real defence if the Brazilian fullback proves to be attack-minded as usual.
"It's a difficult one to analyse because both teams can be unbelievable and both can be average at times, even within the same game," Murphy said speaking on Friday's Alan Brazil Sports Breakfast.
"Salah has obviously been incredible ad he's such a threat, and Real Madrid probably have the best attacking left-back in the world in Marcelo.
"Is he going to do what he normally does and just fly forward, forget who is behind him and take a risk that Real keep good possession and make those runs forward, or is he going to be a bit more disciplined in keeping an eye on Salah?
"That's one area of the pitch I think could be fascinating.
"It's one of those fascinating games where within 20 minutes Liverpool could be 2-0 up or 2-0 down."