Manchester United has been ranked football's most valuable team by Forbes magazine for the sixth straight year as a group of investors and fans try to buy the heavily indebted club. The American business magazine's valuation is $1.8 billion, but the Glazer family owners are resisting the hostile Red Knights campaign to buy the 18-time English champions and their debt of $1.1 billion. Taking into account revenue growth, profitability and debt levels in the 2008-09 season, Real Madrid is second at $1.323 billion, with Arsenal third at $1.181 billion - the same top three as last year. Barcelona has leapt to fourth from seventh after winning the Champions League plus a Spanish league and cup double.