The striker enjoyed an impressive season for the Portuguese outfit, scoring 13 goals in all competitions, with ten in 19 appearances in the league.
He has two years remaining on his current deal but the club would look to sell should an lucrative enough offer be made for his services. The reports claim that they have set an asking price of €8million for their man, which would work out at around £5.8milliion.
Both Everton and AFC Bournemouth, as well as potential suitors Galatasary and Fenerbahce, wouldn't be interested in a deal at that price, although considering his release clause is €30million, it would represent a fairly decent price for the striker, with the Blues in particular need of attacking reinforcements to help ease the burden on Romelu Lukaku.
However, given that recent reports suggest Roberto Martinez has as little as £20million to spend this summer, it is unlikely he would spend just over a quarter of his transfer budget on one player, especially with other areas of the team in more desperate need of improvement.