Chiefs first five-eighth Aaron Cruden faces a lengthy spell on the sidelines after breaking his left thumb in his side's 43-43 draw with the Cheetahs on Sunday.

The side's co-captain is expected to be out for six to eight weeks, a major blow for the defending champions and New Zealand Conference leaders.

After Sunday's dramatic draw, Cruden went to hospital for an x-ray which identified a fracture in the thumb. Cruden has scored 47 points for the Chiefs this season.

The injury means he may not return before the international break and puts him in doubt for the All Blacks first test against England on June 7.