United officials have been sounding out Benfica about Di Maria's availability but have been deterred by an insistence that he will cost every last penny of the release clause in his contract.
A compromise could be on the cards, though, following claims in Lisbon that Benfica would at least consider a swap deal that would entail United parting with Anderson plus a £10m cash adjustment.
Top target: Manchester United are determined to land Di Maria
Deal breaker: Anderson could leave Manchester United to join Benfica
With the 22-year old midfielder yet to fulfil the promise that landed him an £18m move to Old Trafford from Porto nearly three years ago, United manager Sir Alex Ferguson may be prepared to sanction such an offer to secure one of his main summer transfer targets.
It will require decisive action by Ferguson to win the race for Di Maria, following reports in Argentina that Real remain firm favourites to sign him.
The United manager has been monitoring Di Maria's impact all season and has seen enough of his lightning pace down the left and eye for goal to be convinced that Diego Maradona was not exaggerating in a recent analysis of the Argentina international's worth.
'I have been following his progress in Europe, and I am more certain than ever that he is going to develop into a true world superstar in the next few years,' said the Argentina coach.
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