The Egyptian joined the Blues when Jose Mourinho was in charge in the early 2010s.
Ex-Blues star Cesc Fabregas told the Planet Premier League podcast: "He's a very special talent. I played with him at Chelsea for six months. He is a top guy as well and has a good mentality. I am happy for him. as he is a very, very hard worker. He believed in his talent, went away and found his way.
"Now he is showing everyone how good he is. Maybe it was lack of chances [at Chelsea]. You could see his trends. You could see he was quick. You could see that he was attacking the spaces.
"But then when he had one against ones, maybe he was not as strong as he is now. He was not so prolific in front of goal. Players need chances, they need someone to believe in you and he's had that at Liverpool.
"He had that at Fiorentina where he went on loan for six months to show how good he is. I remember a solo goal he did there as soon as he arrived. We were all in the dressing room 'Oh my God did you see Mo's goal? He never did that here!' We were talking like this."