Casemiro joined Manchester United from Real Madrid at the start of the season and has played a big role in transforming the English side's fortunes in recent weeks under their new Dutch manager.
United have recovered from a slow start to the season and are now closing in on the top four while they have sealed progress from their Europa League group into the knockout rounds.
Casemiro arrived at Old Trafford as a five-time Champions League winner from Los Blancos but despite the enormous success he has enjoyed in his club career, the Brazilian says Ten Hag's desire to win is commendable.
"After being in football for quite a while even though I'm only 30, his obsession for winning is what surprised me the most," he said in a press conference ahead of Thursday's Europa League clash against Real Sociedad.
"I think he's got many strengths, we all know it's a process and we're growing together. We want to win and he is obsessed with teaching us and making us better to the millimetre.
"That obsession with winning is something I've only seen with very few managers."
Ten Hag was equally effusive about Casemiro's impact since his arrival.
"He told me he needs a new challenge because at Real Madrid he won everything," he said.
"He was a big part at Real Madrid and they didn't want him to go but he had the feeling 'I have to go to another club, another league to prove myself and that shows his hunger. I really like that.
"From the first day he has come with that attitude in every training, every match and I really like it. He will be more and more important to our team."
