Luke Shaw has said that the Manchester United defenders feel more secure when Casemiro is on the field.
The Brazil international is currently serving a Premier League suspension, missing the last two matches against Leeds United following his red card against Crystal Palace.
Casemiro will also be absent against Leicester City in the league this weekend, but he is available to feature in the Europa League and has travelled to Spain with his teammates for Thursday's Europa League knockout round playoff first leg with Barcelona.
The 30-year-old has been a key player for Erik ten Hag's side since his arrival, featuring on 30 occasions in all competitions, contributing four goals and five assists, and Shaw has lavished praise on his teammate ahead of the European contest at Camp Nou.
"I think it's been quite obvious to see how important he is to the team when he's not been playing," Shaw told reporters on Wednesday evening.
"For us as defenders, he gives us that feeling that we know there's a lot of security, especially because of his positioning, where he always is.
"He loves to win the ball back and tackle. We always say to him that he likes to give the ball away so he can go and win it back.
"I think he's an extremely important player for us and I'm very happy to have him back tomorrow night because, like I said, he's been a big miss for us."
Shaw also opened up on Man United's improvement since losing their opening two matches of the season to Brighton & Hove Albion and Brentford in the Premier League.
"I think obviously not just myself but I think the team in the first two games was nowhere near where we should have been at," said Shaw.
"It was obviously a very difficult start but I think we've learned from that and we've grown as a team, not just as individuals, but as a team.
"I think now collectively it's showing in our performances and where we're going. Of course, it helps with the manager, he's been really good and has shown a lot of trust in me. My main thing now is to repay that trust with good performances and to help the team as much as possible."
Shaw also said that the Man United players are "looking forward to" testing themselves against a Barcelona side who have won each of their last 11 matches in all competitions.
"It's obviously a very big game, it's one we're all looking forward to. And yes, it's going to be a big test, it will show us where we are. But I think where we are at the moment, we're ready for it," he added.
Shaw, who could potentially be used as a central defender at Camp Nou due to Lisandro Martinez's absence through suspension, has scored once and provided three assists in 27 appearances for Man United this term. body check tags ::