Erik ten Hag is confident Casemiro will bounce back from his calamitous Liverpool display and is ready to compete with Manchester United new boy Manuel Ugarte.
The 32-year-old star arrived from Real Madrid shortly after the Dutchman's appointment in 2022 and enjoyed an impressive start to life at Old Trafford.
But Casemiro failed to scale such heights last season and produced an alarming display against Liverpool a fortnight ago, gifting them two goals before being substituted at half-time of the 3-0 Old Trafford loss.
Talk of a potential departure during the international break failed to materialise and Ten Hag is counting on the midfielder as United's return to action at Southampton.
"Definitely need him, for sure," the Dutchman said. "And of course I speak with him about the situation, but everyone can have a bad at the office, or do you never have a bad day at the office?
"Of course it's a different approach (to dealing with a young player). He is experienced and it's not the first time, I guess, he has dealt with a bad game and now he has to overcome this one as well.
"But that is normal in life. You have highs and you have lows.
"That is in your life and also in the life of a football player, only for a football player of course that is obvious. There are many observing this and have an opinion about this and also you have to deal with this.
"But he knows how to deal with it and nobody's career goes only up, no team level, team pattern is only going up.
"You have to deal with it but then it's about what is the end result."
Casemiro's Liverpool nightmare came on the same day new signing Ugarte was introduced to the Old Trafford crowd.
The 23-year-old has been in United's crosshairs all summer and joined on deadline day from Paris St Germain for an initial 50million euros (£41.1m) that could reach 60m euros (£50.5m).
Asked if he spoken to Casemiro about Ugarte's arrival, considering their similar profiles, Ten Hag said: "Normally I do, yeah, and also in this case I did as well.
"But such players, in our club especially, you know when you are playing on this level that there is always competition.
"Because they also know in this club you can only be successful when you have a squad where you have to cover five leagues.
"You can't have a squad where in positions we have only one player who can cover this, so you need at least two players in every position who can cover this. Sometimes it's three for two.
"It's OK when you have very robust players. But he understands, all the players will understand and then it's about what is the best fit for the team?
"They have to prove it and the key word is they have to take responsibility to win games for your club."
Ugarte first caught Ten Hag's eye in Champions League group stage three years ago, with United's scouting team also judging "he would be a really good fit for our team".
"I played him already as manager of Ajax when we faced Sporting Lisbon," he said. "He's quite a long time on my radar.
"He's coming in, a late transfer coming in, but he's playing in a very important position.
"You have to connect defending with attacking, and attacking with defending.
"Communication is very important there to guide the team, to lead the team, to make the connection between attacking and defence, defence and attacking.
"We have to help him, we have to guide him about how he has to play that role but what we have seen he knows a lot already a lot. "He has the profile where we think he can fit in that role and now we have to teach him some details about how it works in our team."
Chief executive Omar Berrada publicly backed the Dutchman before the Liverpool defeat, but he knows results are needed as United bid to avoid a third successive loss.
"In football you have to win," Ten Hag said. "In football you have to deliver. That's clear.
"But, as I've said, I have delivered here and it's good that the new leadership acknowledge this, that they tell us, and we are here together.
"We are working together to be even more successful because we have higher targets than we've already achieved."
