The Egyptian winger's sensational form has only made Roma's decision to sell him to the Reds last summer for €42 million look all the more ludicrous.
With that in mind, Goal has decided to look back at other clearly talented players who were sold on the cheap.
It is worth noting, though, that we've excluded all free transfers, as well as players who were unknowns at the time of their respective moves.
However, have we overlooked anybody? Let us know your thoughts in the comment box below...