Manchester United have received a boost in their pursuit of Sporting Lisbon midfielder William Carvalho, with reports in Italy suggesting Inter Milan cannot afford him.The San Siro giants who, like United, have under-performed this season, are keen to rival the Red Devils’ interest but are struggling to raise the funds, according to Tutto Mercato Web.Portugal international Carvalho has a 37million release clause which the report claims is not out of the Premier League club’s reach, but represents a massive stumbling block to Inter.TMW reports that Inter have been in contact with Sporting and put an offer of 12million on the table – significantly less than the Portugese club’s valuation.It was apparently given short shrift and Sporting will instead hold out for the full amount once Carvalho has completed his World Cup campaign in Brazil this summer.United continue to monitor the situation with interest despite sacking David Moyes as manager last week.