CHICAGO -- Luke Shaw has backed Ruben Amorim's attempts to change the "toxic" culture at Manchester United and said the Portuguese coach is right to exile "stragglers" from the squad.
Shaw said Amorim is determined to raise standards at Old Trafford following United's worst season for more than 50 years.
And the England defender has revealed that the 40-year-old has made it clear that any player who falls short of his demands will find themselves out in the cold.
"The mentality is a big thing on his lips," Shaw said.
"I think he talks a lot about it. Ruben demands 100% and that's it and he doesn't want anything less. If someone's doing 85 or 90%, it's not enough for him. I think, especially this year, if you're not doing the right things, I feel like you won't play.
"It's not hard to see from the outside what it's been like. A lot of the time I've been here over the last few years it's been extremely negative. It can be quite toxic, the environment, it's not healthy at all.
"We need an environment that's healthy, that's positive, that's got good energy and happiness."
Amorim, who was appointed in November, has already made his mark on the United squad.
Marcus Rashford has been loaned to Barcelona while a group of players -- Alejandro Garnacho, Antony, Jadon Sancho and Tyrell Malacia -- have been omitted from the preseason tour of America.
Amorim has also made a point of saying new signings Matheus Cunha and Bryan Mbeumo were brought to United primarily because they expressed a strong desire to play for the club.
"There are no stragglers in this group any more," Shaw said.
"I think you've seen what he's done in the past eight months with different players and things like that, he doesn't care who the player is.
"I think if he's not following what he wants, then that's how it should be, and I think rightly so.
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"His mentality, his demands, he's extremely tough on the group. Everyone has to put the team first. He's made that very clear. As players we're fully behind him and fully behind on his ideas and what he wants to implement in the team.
"I feel like at the end of the day, the manager has to do that because he's going to be the one that his job is always on the line."
Amorim is already under pressure after United's 15th-place finish in the Premier League and defeat to Tottenham in the Europa League final.
The tour of the U.S. is being used as a reset for both players and staff ahead of the new campaign.
And Shaw, United's longest serving player, has promised to help his manager's push to raise standards within the squad.
"I think us as players, especially the more experienced ones, we need to be demanding more from a day-in, day-out basis," he said.
"The levels in training, keeping the times of when we're doing this and doing that, making sure no one's coming late or anything.
"I think whatever the manager wants, us as players we have to be delivering that. We're fully behind that."