Cristiano Ronaldo told a Madrid court last week he wants to return to England, Sky sources understand.
The Real Madrid forward appeared in court last Monday to deny he had evaded about £13m in tax by using three off-shore companies based in the British Virgin Islands.
Ronaldo told the court he believed he had paid more tax than he should since he moved to Madrid eight years ago.
At one stage during his 90-minute appearance, Ronaldo said: "I never had these problems in England. That's why I want to go back there."
Manchester United sold Ronaldo to Real Madrid for £80m in 2009.
United manager José Mourinho said last month it would be "mission impossible" for him to re-sign Ronaldo.
The Old Trafford club have distanced themselves from reports linking them with a move for Ronaldo and Sky Sports News understand they do not want to be involved in a media circus surrounding his future.
Ronaldo signed a new-five year Real Madrid contract last November.
United play Real Madrid in the European Super Cup final on Tuesday.