The Brazilian, whose brother Rafael also plays for the Red Devils, has found himself behind veteran left-back Patrice Evra and Dutch defender Alex Buttner at Old Trafford.
Former United boss Sir Alex Ferguson, who was replaced by David Moyes in the summer, sent Fabio on a season-long loan to Queens Park Rangers last season.
And the 23-year-old admitted he may have to leave in the January transfer window to revive his stalling career.
“I think the time has come and maybe in the next window or even next season, I think I might leave. There are good possibilities,” Goal.com quotes him as saying.
“I’m looking for other clubs. There’s nothing certain, we’ll leave it for later.
“I want to be happy. I want to play, I want to be close to my family. I may go back to Brazil, or maybe not, I’m checking with my manager to see what is the best for me.”
Fabio moved to United from Fluminense in 2008, and the South American spoke of his connection with his former club.
“The affection I have for Fluminense is very big, for sure. I played there for seven years, and certainly if I have to go back to Fluminense I’m going with great pride because I have a special affection for them,” he added.
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