He stated: "I think we needed the six (holding midfielder) when I arrived here and last season Casemiro was fantastic. I don't think he ever scored so many goals as well but as a six, a holding midfielder, a strategist, he was so important for the team.
"This season he struggled with a bad injury he's never had in his career but he is such a winner, all his career he's won. Everywhere he goes, there will be success, and I trust he will give his success. I know he will need games, he will be better, and I'm very confident about him. He is a fighter, that's why he's won big trophies. He's a very important player and will give us success."
Ten Hag also revealed Alejandro Garnacho has apologised for his social media antics after last week's draw at Brentford.
He added: "Alejandro is a young player, has to learn a lot. He apologised for it and after that we move on."