Oscar, 21, has made a number of eye-catching performances for the Blues since arriving from Internacional in the summer and has already notched up three goals and three assists in nine appearances.
And the 18-year-old Piazon, who moved to Stamford Bridge from Sao Paolo last year, was handed his Chelsea debut in the Capital One Cup victory over Wolverhampton Wanderers last month.
“We’re very happy to have these Brazilians in our team,” said Di Matteo. “They are very good players and a joy to work with – they’re classic professionals.
“Oscar has settled in very quickly and I think the fact that we already had a few Brazilians here and Portuguese and Spanish-speaking players has helped him a lot, and that’s always an advantage.
“Lucas Piazon is a young, talented player that has come into the first-team squad this season. He’s made an appearance in the cup and he’s somebody that we would like to progress. He has a good chance of becoming a top player.”
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