Lucas Silva's move was confirmed yesterday.
"I'm obviously sad as a coach because I lose a great player," Oliveira said.
"When I arrived at Cruzeiro Lucas was hardly playing and under me he began to enjoy more minutes on the pitch. He has worked hard and he became a starter on merit. I'm very happy for him, as a friend and as a former player. I'm also very happy to see the success of a footballer of mine."
He added: "He is a very technical player, he has vision, accurate passing of 30-40 metres, has a strong and very good shot.
"Lucas is an exceptional person, he trains well, is very polite and is a good professional, always listening to guidance and he wants to learn."
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