Casemiro insists "age is not an issue" and the midfielder is feeling optimistic about the future at Manchester United.

The Brazil international and his team-mates have endured a frustrating season at Old Trafford, with the club in danger of suffering their lowest Premier League finish in eighth place.

Casemiro enjoyed a successful first campaign with the Red Devils, who he helped to a third-place finish and victory in the Carabao Cup.

However, injuries have prevented the 32-year-old from building on that momentum this term, with critics suggesting his age is preventing him from coping with the physical demands of the English top flight.

But the former Real Madrid midfielder rubbished those suggestions, highlighting notable examples of players shining in their mid to late 30s.

"I feel very well, very well," he told Sky Sports. "I feel healthy, with energy and the same mentality I always had.

"I guess people end up talking about the age factor, but it's been proven. Recently, our friend Thiago Silva - at the age of 39, came here and showed that, yes, you can play. The previous Ballon d'Or winners were over 34.

"At Manchester City, there's Kevin De Bruyne. (Mo) Salah at Liverpool. I think age is not an issue, it is not a factor in this, but analysing one's game and knowing about everything that is happening around the game.

"These are people who analyse football well, who see what's happening, who know what's happening, and not analyse the age.

"But I'm well, I'm happy. As I usually say, Manchester United gave me what I wanted - this joy of being able to enjoy the game, enjoy the Premier League. So, I'm happy to be here."

United conclude their Premier League season away to Brighton and Hove Albion on Sunday, before facing rivals Manchester City in the FA Cup final on May 25.

Casemiro believes the vast number of injuries have played a crucial factor in the Red Devils' struggles this term.

"It's been a season of a lot of sacrifices for all of us, with the injuries and players adapting," he added. "So, it's been very hard for us.

"The manager came to ask me [to play at centre-half], and I told him I'm always available. That's the way I am; trying to help, committing to the team and to the coaching staff. So, when he asked me, I didn’t even hesitate.

"I think we had over 60 or 70 injuries. I've never seen this in my life. 

"It is hard to think about winning a Premier League when you have so many injuries to important players, players that you think will be able to play throughout the season, and you can't count on them."