Perez has been in sensational goalscoring form for Newcastle in recent weeks.
"He meets the profile of our homegrown players," said Rivero.
"He is serious, hardworking and respectful of our methods.
"He is different, a skillful dribbler and has a very good first touch. There are many technical resources. We knew he would make it, it would all depend on his competitiveness.
"He now has shown that and it's hard to estimate what is his ceiling."
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