The midfielder joined Jose Mourinho’s side from Shakhtar Donetsk in the summer for £52 million ($68m) but has failed to hold down a regular spot.
Indeed, he has appeared only 10 times in the red of United and has totalled a mere 645 minutes of pitch time.
A consequence of this has been the 25-year-old losing his place in Tite’s Brazil squad just six months out from Copa America 2019.
“I’ve played very little at United, so it’s normal for Professor Tite not to be able to evaluate me, even though I’ve worked hard with him before,” he told reporters.
“Of course, I was annoyed, but I have to know how to deal with the sadness to be able to help me take a step forward.
“The coach has chosen not to put me in the team. That’s his choice. I still do my job and I can’t let it affect my mindset, I cannot let that shake me. I have to be patient.”
Indeed, he has found the settling process in the Premier League somewhat complicated.
"It’s been a bit of a difficult start for me at United because I have not been playing so much. I had a lot of games in Shakhtar, but it’s a little bit different here. It’s normal, of course, a process of adaptation to a different league.
“Although I’ve been to Europe before, now I am in a different country and I have to go through a new process of settling in. But today I see myself much better and I hope that my football will be 100 per cent soon.
“I think I had a great performance against Young Boys in the Champions League. We had the opportunity to score a few times before we scored the goal at the end, but I was very happy to have returned to the field and I hope to continue playing more.”
United struggled to a 2-2 draw against Southampton on Saturday – a match in which Fred remained on the bench – and will attempt to bounce back at home against Arsenal on Wednesday.