The Brazilian, who now plays for Cardiff in the Championship, won the Premier League title in 2010/11 and has been capped twice at senior international level.
Although initially highly-rated at Old Trafford, he struggled for game time before joining the Bluebirds in 2014, where he has since impressed.
And now reports claim that he’s a target for newly-promoted Premier League outfit Middlesbrough, with Aitor Karanka looking to bolster his full-back options.
The 26-year-old is now in the last 12 months of his contract in South Wales, which will tempt Cardiff into selling before the close of the window, at which time his value will fall significantly.
Rafael, who could not steer his side clear of relegation in the 2013/14 season after his January move from Man United, could be the latest notable signing for Boro this summer, with the Teesiders having already moved to snap up the likes of Alvaro Negredo and Victor Valdes, who have won titles in England and Spain respectively.