Sissoko supports Juventus pair Melo, Diego
The Brazilian pair have failed to live up to expectations since their summer arrival.
But Sissoko says: "Juve has spent so much on Diego and Melo. They're currently going through a difficult moment, but I believe they can both help the team, already starting with the challenge against Catania on Sunday."
He added: "I have a contract until 2014 and I'm happy here."