Ghana defender Isaac Vorsah has been ruled out of action for six weeks after damaging ligaments in his knee.

The 20-year-old, who plays for German side Hoffenheim, was taken off during Saturday's league clash with Hertha Berlin. Hoffenheim doctor Pieter Beks says the Ghana international will need six weeks of treatment to fully recover from the setback.

This means he will miss Wednesday's friendly against Bosnia in Sarajevo. Vorsah was a key player in Ghana's squad as they finished runners-up at the Africa Cup of Nations in Angola last month.

He is expected to play for the Black Stars at the World Cup in South Africa in June.

Meanwhile, Vorsah's compatriot Opoku Agyemang is likely to miss the World Cup because of injury.

The 20-year-old, who plays for Qatari side Al Sadd, suffered the knee injury during their Asian Champions League clash with Saudi outfit Al Hilal last Wednesday.

Doctors from Al Sadd say he will be out of action for six months and he will undergo surgery in France this week.

However, Agyemang is hopeful of a speedy return to be able to play for his country at the World Cup in June.

Agyemang was a revelation for the Black Stars at the Africa Cup of Nations in Angola in January and was primed for a World Cup place in South Africa.