Cristiano Ronaldo caused a stir in the Manchester United dressing room by jetting off to Portugal after he was ruled out of facing Manchester City.
The Portuguese striker, 37, sustained a hip complaint late last week and played no part in United's 4-1 defeat at the Etihad on Sunday afternoon.
"Cristiano had some problems with his hip flexor on Friday and since then, he didn't train," interim manager Ralf Rangnick said ahead of kick-off.
Ronaldo is the Red Devils' top scorer this season with 15 goals in all competitions, so his absence came as a major blow.
The five-time Ballon d'Or winner has talismanic status on account of his record-breaking career and he is a senior figure in the squad.
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But Ronaldo was conspicuous in his absence at the weekend and did not make the short trip across town to attend the match.
Instead, The Athletic claims he flew to his native Portugal in a move which surprised his teammates given the magnitude of the fixture.
While United do not require their injured players to attend matches, the report adds Ronaldo's colleagues felt they would have benefited from his presence given the high regard he is held in.
They will hope he recovers from the hip issue - which also ruled him out of January's 2-2 draw with Aston Villa - in time for the visit of Tottenham on Saturday evening.
Rangnick did not provide a timescale for Ronaldo's recovery but simply insisted he is unavailable after pundit Roy Keane raised doubts over the cause of his absence.
"There seems to be something more with the Ronaldo situation, the manager coming out talking about his hip flexor but the man is a machine and is rarely injured," Keane told Sky Sports.
"Every now and again he comes out with that about his hip flexor, doesn't add up to me."
Rangnick responded after the Manchester derby by saying: "I have to believe our medical department.
"Our doctor came to me on Friday morning to say Cristiano couldn't train because of some problems with his hip flexor and the same on Saturday."
Ronaldo had been short of form prior to suffering a recurrence of his hip injury with just one goal to his name in 2022, which came against Brighton in mid-February.
Rangnick was also without Edinson Cavani for the trip to City as the Uruguayan centre-forward was short of fitness, so he deployed an unconventional 4-2-4 system using Bruno Fernandes and Paul Pogba up front.
