Emerson talked up the England internationals before last night's draw with Burnley.
He told Goal: "Ruben will, according to me, become one of the most important players in the world because he is a central midfielder who has it all.
"He is quick, he knows how to defend and attack, and he will become a very important modern midfielder. He is a fantastic player who will be even better."
Emerson continued: "It's the same with Callum Hudson-Odoi. According to me, Callum is Chelsea's future. He has already shown that he is very good at the age of 18, and he has done so in Chelsea, which is a big team. According to me, he will be at his peak in two or three years."