Palhinha played for Amorim at Sporting and told O Jogo: "Ruben is a coach with a lot of quality, one of the best in Portugal. He has done an excellent job since Braga.
"He has in-depth knowledge of the game and has a close relationship with the players.
"The way he is growing, he won't stay in Portugal much longer. It will not be for lack of opportunities that he will not leave Portugal.
"He dreams and aims to win another title with Sporting and then the future will be in his hands."
He added: "Yes, of course, although the pressure is different.
"When you coach a big Portuguese club, you have pressure from the fans and the size of the club itself, which forces you to win.
"When you coach Liverpool, you have pressure from the fans, the club and the whole world. The way it is developing, I think it will be a matter of time."