He's won the 'Bola de Ouro' which such players as Kaka, Zico, Robinho & Tevez have won so there is no reason he can become a great like one of them.
Lucas Leiva is only 20 years old, same age as Obi Mikel and Cesc Fabregas, there is no doubt he can become as good if not better than them.
He is the U20 Brazil captain who boast such players as Renato Augusto, Anderson, Denilson and Alexandre Pato.
Barca, Juventus, Inter & Athletico were also interested in him.
To give you a clue what he plays like then watch:
or
Lucas might be as good as Fabregas 
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