Manchester United boss Erik ten Hag's attention to detail and obsession to win have impressed Casemiro in his first few months at Old Trafford.
"I've been in football for quite a while despite being only 30 and his obsession for winning is what surprised me the most," said Casemiro, who played under Zinedine Zidane and Carlo Ancelotti during his time at Madrid.
"I think he's got many strengths. We all know it's a process and we are growing together and we all see that he wants to win.
"But his obsession for teaching us and leaving everything perfect to the millimetre, that is key.
"His obsession for winning is something I've only seen in very few managers."
Ten Hag surprised many by not throwing Casemiro straight into the team following his £70 million move ($81 million).
The Brazilian was left on the bench for his first four Premier League games, but has been instrumental in United's current eight-game unbeaten run.
And Ten Hag hailed the midfielder's desire to seek out a fresh challenge after a glorious era of success in Spain.
"He told me when we had the first talk he needs a new challenge because at Real Madrid he won everything," said Ten Hag.
"He was a big part of Real Madrid still, they did not want him to go. But he had a feeling, this is what he told me, he had to go to another club, another league, to prove himself.
"That shows his hunger and I really like that and I think from the first day he's come with that attitude, to every training session, every match and he proves it and I like it. He will prove more and more important for our team."
United travel to Real Sociedad on Thursday needing to win by two clear goals to usurp the Spaniards at the top of Europa League Group E and secure a place in the last 16.
Both sides have already qualified for the knockout phase with second place in the group facing a playoff against a side that has dropped down from the Champions League.