Manchester United and Chelsea have been asked to stump up £25 million if they want to sign highly-ratedBenfica defender David Luiz, according to the Daily Mail.

    The 22-year-old has been watched extensively by both clubs in recent times, with United in particular keen on the Brazilian as both Rio Ferdinand and Nemanja Vidic have missed a number of games this season.

    Chelsea have also closely monitored Luiz, who is a former Brazilian Under-20 international, but with Barcelona, Real Madrid and Inter Milan also reportedly interested the Portuguese side are looking to hold out for a sizeable transfer fee.

    Luiz has played in 25 of his side's 26 league games this season, in which Benfica have conceded just 14 goals. Os Gloriosos are currently on course to win their first league title since 2005.