Reports resurfaced on Tuesday that Coentrao could be a target for the Premier League club, with the full-back having struggled for games at Real this term.
With Marcelo a preferred option for Carlo Ancelotti at left-back, Coentrao talked up the prospect of playing for United.
"I already showed that interest in playing there [at Manchester United]," the 27-year-old told O Jogo.
"It’s one of the best clubs in the world, a club that I admire a lot. It would be an honour to play there."
On his inability to become a regular at the Santiago Bernabeu of late, the former Benfica defender added: "I hope to have more minutes at Real Madrid and that the coach trusts me more.
"[That is] something that has not been happened so far."
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