Manchester United have been linked with a summer move for Benfica defender Ezequiel Garay on numerous occasions over the past few months.
They have even sent chief scout Martin Ferguson to watch the Argentine in action, who scored for Benfica in their 3-0 win over Guimares on Sunday.
United are looking at Garay, 26, as a younger replacement for Rio Ferdinand, and with long-term doubts over the fitness of Nemanja Vidic.
Barcelona need a new central defender with Carles Puyol suffering regular injuries, with the club recently exposed against Milan and Madrid and are looking for a partner for Gerard Pique.
Garay is an interesting option for Barcelona, most notably because he is a former Real Madrid player.
He spent two-and-a-half seasons with the club, with a year out on loan, and did play under Jose Mourinho for a short period before being sold.
However it is thought this is not a reason which would prevent him from joining Barcelona, as he would have the opportunity to play alongside Argentinean international colleagues Lionel Messi and Javier Mascherano who he is good pals with.
Barcelona were said to have tried to sign him before he went to Madrid but were outbid, and will have to fight off Manchester United and potentially Chelsea for his signature.
Garay will cost around £15 million but Benfica will look to push that higher and spark a bidding war with Europe's top clubs chasing the centre-back.
Should United be concerned about Barcelona's interest?
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