Carrick opened his time as manager with victory over Manchester City last week and takes United to Arsenal today for his second game in charge.
The Sun says senior players are happier with Carrick's short, intense training sessions, which have also been more enjoyable compared to Amorim's
A source stated: "Amorim’s sessions were gruelling but boring.
“He would focus so much on tactical detail and the players would be out on the training pitch for a long time, but sometimes without intensity.
“The information they had to take onboard could leave them feeling mentally drained.
"Under Carrick it’s been very different. Shorter, sharper sessions which the players are enjoying more.
“They think the performance against City was a direct result of Carrick’s approach.”