Rennie is expected to name his team on Thursday
The defending champion Chiefs were forced to call up some reinforcements for the second leg of their South African tour.
The Chiefs will play the Kings in Port Elizabeth on Friday.
Chiefs hooker Mahonri Schwalger and prop Ben Tameifuna will be returning back to New Zealand and be replaced by hooker Rhys Marshall and prop Michael Kainga.
Schwalger has cartilage damage in his knee, which has not healed as quickly as expected and Ben Tameifuna is returning home on family bereavement.
Marshall has had an impressive start to his Super Rugby career, playing against the Highlanders and the Cheetahs.
Kainga, from the wider training group, has yet to make his debut, but was strong in the pre-season trials.
After their encounter with the tournament rookies, the Kings, the Chiefs will return home to play the Highlanders in Hamilton on Friday, March 22.
Coach Dave Rennie is expected to name his team to play the Kings on Thursday.