Zisis suffered the injury in a nasty collision with Anderson Varejao of Brazil in the second half of Greece¡¯s 91-80 Group C victory on Wednesday night.

Zisis, whose three-pointer in the final seconds gave the Greeks a 72-69 triumph over Australia on Tuesday night, cut into the lane with the ball and after passing, was knocked to the ground by Anderson.

The referees did not see the incident and no foul was called.

Greece¡¯s team-mates immediately surrounded Anderson to complain and the referees had to restrain the players but Zisis left the contest and played no further part in the game.

Zisis spent the night in a Hamamatsu hospital and will remain there for three more days but he will not play at least for six weeks.

Panagiotis Yannakis, the Greece coach, said: "Nikos is a strong guy mentally and will recover from this very fast, now we have a problem replacing him but we will try to replace him with team-work."

Greece players met with reporters and said they had spoken to Zisis, who¡¯d asked them to keep winning games for him.

Zisis, 23, has had a very good year, helping Greece win last year¡¯s EuroBasket and earning FIBA Europe¡¯s Young Player the Year award.

He missed part of the 2005-06 campaign with a hand injury but returned to Benetton Treviso in time to help them win the Lega A title.

Greece take on Turkey in a battle of unbeatens on Thursday to determine which side finishes top of Group C.