London Standard
Chelsea Football Newsletter
Mainoo on Friday posted a series of images on Instagram of him taking part in individual training drills, looking pensive and in the gym on his own.
The fourth of five images was from the film 'Whiplash', and specifically of the lead actor, played by Miles Teller. The highly acclaimed 2014 film tells the story of a toxic relationship between a music teacher and one of his students, played by Teller.
The teacher, played by J. K. Simmons, has highly controversial methods, which include being verbally and physically abusive, manipulative and relentlessly strict. Teller's character eventually pleases his teacher, but at a significant mental and physical cost.
Mainoo post comes days after the transfer window closed, during which he tried and failed to get a loan at from United despite falling down the pecking order under head coach Ruben Amorim.
The young midfielder has also lost his place in the England squad, which on Saturday faces Andorra in a World Cup qualifier.
Palmer has sent tongues wagging with his abrupt comment on the Instagram post, which read: "3 my boy."
Mainoo and Palmer are long-time friends, having both grown up in Manchester before the latter's move to Chelsea. The pair have also spent time together at past England camps. Last year, they were partnered together for GQ's Men of the Year issue.
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It has been suggested that Palmer simply means 'free my boy', in regards to his failure to leave Manchester United.
The post has garnered over 20,000 likes at the time of writing.