Lampard was a team-mate of the Egyptian for six months before his own Chelsea career came to an end that summer.
"Unfortunately for Mo, it didn't work out here but it is great credit to him. He went to Italy and then came back and now he's a superstar," said Lampard.
"As for his path, it's hard to compare what might have been. The talent was obviously there.
"At the time, I think we had a lot of options in attacking areas. Number 10s, wingers, and he didn't get as many opportunities for whatever reason, but yes, you could see the talent was there.
"But the player that he is now, or that came back to Liverpool, I think you have to say huge credit is due. You don't have to search for anything more than look at Mo himself.
"You have to say what professionalism and work ethic, to leave a club like Chelsea is not easy.
"People then cast you aside and say you won't make it there. He went on to be the superstar he is now. It is completely credit to Mo himself."