Manchester United midfielder Fred says the players need to get rid of any dressing-room cliques if the club is to rise again under Erik ten Hag.
Last season was United's worst in the Premier League era amid rumours of divisions and a toxic atmosphere within the team.
Fred warned that cannot happen again if Ten Hag is to turn United's fortunes around, but believes the Dutchman has already started to tackle the issue with 'new rules'.
Ten Hag is said to have laid down the law to his players, telling them that they have to put the team ahead of themselves.
'We have to be united,' said Fred in Bangkok on the club's pre-season tour to Thailand.
'All aspects of last season were difficult which is hard. This season with a new manager, with new rules already, we'll look to unite and stick together as that's how our team must be.
'We have to be strong, and to be strong we have to be united. We hope we can be focused and strong. Erik can help us to continue being united. For some years now we haven't won any trophies.
'Obviously something has to change to achieve success. If it's not working you have to aim to succeed. I'm certain Ten Hag is aware of this and will do his best to help Manchester United return to the top, from where they should never have left.
'It's really important for us to have a strong coach who has the last word alongside us. It gives us security and helps us a lot.
'He's very detailed in his work, he has his own fine details. All the day-to-day details. It's really good for our daily work. Everyone on the pitch has to give their all to help the team.'
Fred acknowledged that last season was a tough experience for everyone at the club, but he has already seen enough of Ten Hag to believe he is the man to put things right.
'Last season was difficult, but that's in the past now,' added the Brazilian. 'We know it wasn't good, it wasn't what we wanted. I'm certain that Erik is here to do great things, he's here to win things.
'We really hope he can do a great job here and are fully behind him. We're looking to achieve a lot, great things, and I'm sure we'll achieve this.
'He's a great coach. Training is good, intense. We're aiming to put what he says into our daily training. I hope we can win things in the future. It obviously won't be easy, it won't happen overnight. We'll look to be doing our best as soon as possible.'
United are looking to make new midfield signings this summer to replace Paul Pogba and Nemanja Matic, but Fred would welcome the competition as he prepares to start his fifth season at Old Trafford since a £52m move from Shakhtar Donetsk in 2018.
'Pogba was a great player here, unfortunately he moved on,' said Fred. 'We wish him all the best. There will always be competition. We're a big club, one of the biggest in the world.
'Players joining us will be looking to play, and those of us already here want to play, so there will be competition. It's been a great four years for me here. It's been really important for me, a club that has both embraced and helped me a lot.
'I hope to continue giving back in games, I have to do my job on the pitch. It's been an excellent four years for me, I want to continue developing more every day and I still want to win a lot of trophies with United.'