Beauden Barrett was scratched from the Hurricanes' squad to face the Bulls overnight as a precaution after suffering a head knock in last week's win over the Cheetahs.
Hurricanes coach Chris Boyd said the source of Barrett's head aches was still unclear, but he had been withdrawn from the Hurricanes'34-20 win by the medical team.
Barrett left the field at halftime during last weekend's win over the Cheetahs in Wellington, passed a concussion test and had shown no symptoms until the team landed in Johannesburg.
Although the team doctor was unsure whether his headaches were due to travel, altitude or humidity, it was decided the day before the match to withdraw him from the Bulls match the day before kick off as a precaution.
Barrett had exercised earlier in the week without any issues, Boyd said.
Head coach Chris Boyd said the match had been one of the toughest under during his tenure with the team.
"In the period I have been with the Canes it's probably the most battered changing room I have seen... we were not great technically or tactically, but we take a lot of positives in the fact we went deep in the well emotionally and did pretty well."
Injuries out of the match included openside Ardie Savea and lock Mark Abbott both coming from the field with head knocks as well as wing Wes Goosen suffering a shoulder injury. 16 Hurricanes players were affected by cramp in the match.
