Real Sociedad defender Inigo Martinez is a target for Europe's biggest clubs.

Martinez returned to pre-season training with his club on Friday but his days in San Sebastian could be numbered as a continental giant is ready to pay the defender's 30 million euro release clause.

Marca says Juventus, AC Milan, Manchester City, Liverpool and Barcelona.

"There comes a time when you consider everything and when I say everything is everything, but I am grateful that the club has done everything possible because I will continue and we can achieve," said Martinez following his renewal.

At the time of the deal, the club neglected to raise the centre-back's release clause and with one year passed, top clubs are ready to pounce.