Sigthorsson, who joined Ajax from Eredivisie rivals AZ this summer, has been ruled out until the winter break after picking up a stress fracture to his ankle during last weekend's encounter with FC Groningen. Former boss Verbeek commented after that setback that he did not know if the Iceland international was strong enough to cope with the demands at the Amsterdam Arena. But the 21-year-old frontman has hit back at those remarks and has vowed to return stronger than ever. "I read that he wondered whether I can physically handle being at Ajax," Sigthorsson told De Telegraaf. "Of course I can. "I am not only physically but also mentally strong. "I have shown that under Verbeek and even in these first few months at Ajax. "Earlier this year Verbeek did not even agree with me on the position I play. And now I play at Ajax he knows it all about me? That's ridiculous." Despite seeing his start to life at Ajax hindered by injury, Sigthorsson is confident he made the right decision in joining the Dutch giants. The striker, who has netted five times for Ajax this season, added: "To me, Ajax is the right club, with a coach who sees me there. "I'll do everything to get fit as quickly as possible. I would like to score and win for Ajax, and make the fans happy. I'll come back stronger."
