Chelsea must go to £40 million to land Porto striker Radamel Falcao.

The Daily Star Sunday says Colombian hitman Falcao, 25, heavily touted to join his former boss Andre Villas-Boas at Stamford Bridge, has agreed to extend his contract by two seasons until 2015.

Falcao's previous deal had a £26m release clause attached but that now stands at £39m.

Porto are aware of Chelsea's interest and want to ensure they don't miss out on a hefty pay day if they are forced to let their star forward go.

The star scored 39 goals last season as Porto claimed four trophies, including the Portuguese Premier League and Europa League.

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