The former Amakhosi captain was a noticeable absentee from Chiefs' first training session on Monday following the return of the players from the Christmas break.
However, Tau will join up with his team-mates at a later date as he is currently in Kimberley helping look after his sister Thulisa.
A statement on the club's official website read: "The Club in its entirety would like to wish Thulisa a speedy recovery and wish that God give the family strength and hope through this difficult time."
Chiefs resume the PSL campaign against basement club Jomo Cosmos at Nelson Mandela Bay Stadium on February 15.