Sonny Bill cleared of knee damage

Sonny Bill Williams has been cleared of knee damage but remains in doubt for the Bulldogs NRL clash with South Sydney on Friday night.

Scans on Williams' knee on Wednesday cleared the superstar of any damage but has revealed a strain to his upper calf muscle.

While the 21-year-old is now relatively pain-free he is still in doubt to play the Rabbitohs, with coach Steve Folkes on Thursday drafting Brad Morrin into the squad as 18th man.

Williams has not trained with the squad all week and will be given every chance to prove his fitness before kick off on Friday.

If Morrin does get called into the side it will be his first NRL game since his infamous biting incident on former Parramatta Eel Timana Tahu last year for which he was suspended seven weeks.