Schalke and Serbia defender Matija Nastasic has been ruled out for the rest of the season after suffering cruciate ligament damage to his right knee.

Nastasic went off in the closing stages of Schalke's defeat to Hamburger SV on Saturday and the club says Thursday's diagnosis means the 25-year-old will be out for eight to 12 weeks.

Schalke says, "Whether he will feature for Serbia at the World Cup this summer in Russia is still unclear."

Nastasic has played a key role in ensuring Schalke has the joint second-best defensive record in the league this season. Only Bayern Munich, the champion, has conceded fewer goals.