The forward is fuming at comments made by United manager David Moyes at the weekend which suggested he was now regarded as a second-choice striking option behind Robin van Persie.
Rooney has taken that as a personal slight on a player who has given nine years' service to the Old Trafford cause and is "angry and confused" about his treatment.
The offending words were delivered to Sunday newspaper journalists during a briefing with Moyes in Bangkok last week.
Moyes said: "Overall, my thought on Wayne is that if for any reason we had an injury to Robin van Persie we are going to need him and I want as many options as possible."
It has been widely interpreted as Moyes stating he regards Rooney as an understudy to the prolific Dutchman. And understandably, that has gone down very badly.
A source close to the situation has highlighted Rooney's unhappiness.
As far as the 27-year-old is concerned, he is at the peak of his career and has no intention of playing second fiddle to anyone, or being reduced to the ranks of becoming a squad player.
With five Premier League titles and a Champions League winners' medal to his name, Rooney does not believe he has anything to prove at United.
Yet he feels as though he has been put on trial by Moyes at a time when he should be concentrating his efforts on recovering from the hamstring injury that saw him sent home from United's pre-season tour within hours of landing in Thailand on Thursday.
"Wayne is confused and angry", said the source.
United are aware of Rooney's feelings and once Moyes and chief executive Ed Woodward wake up on Wednesday morning in Sydney, they will come under pressure to clarify their own position.