Cattermole had a reputation for being overly physical and passionate on the field prior to Poyet's arrival as Paulo Di Canio's replacement in October last year.
That reputation, build on numerous red cards, led Poyet to believe that the English midfielder was "uncontrollable".
But the 26-year-old central midfielder has worked hard to become a key part of Poyet's plans, featuring in 10 of Sunderland's 11 Premier League fixtures this season.
"You come in with pre-conceptions. If somebody tells me, 'This guy is a b******' and I need to be careful, then I will be," Poyet said.
"With Lee, I was told he was 'impossible to control', that 'he will get sent off 100 times' and 'he will let you down so many times'.
"I was told he could not play football like I want to, that he was training on his own away from everybody else - I thought I'd meet Lee and he'd have a gun and he'd shoot me in the head.
"Everything was bad, but these people don't know him.
"Then you train with him and you see his commitment. Everything was 100 miles per hour and we were like, 'Woah, he has learnt a lot'. He isn't just all about commitment and passion, he is always trying to improve.
"He used to go on to the pitch with a certain mentality, but now he's different. Lee has been outstanding. He has probably listened the most to what we have said."
