2) Jackson Martinez (Porto)
A deadly finisher, Jackson Martinez has attracted interest from top clubs all around Europe after his superb performances in his two seasons with Porto. The Colombian international has a fine record of 60 goals in 91 appearances for the Portuguese side, and was rumoured to have been a target for Liverpool last summer. Arsenal and Chelsea have been his main admirers this time around, but there may still be time for Liverpool to join the race for his signature and sign a top-quality strike partner for Daniel Sturridge, who would likely be available for just £27m due to a release clause in his contract.