The 26-year-old fly-half is confident that Wales, who beat England at the weekend, will be more than a match for the defending world champions in Wellington on Sunday, September 11.
Wales produced a strong defensive performance to beat England 19-10 at the Millennium Stadium on Saturday, where Hook scored his team's only try.
"We have played South Africa a lot of times and come close to winning," said Hook.
"But we showed against England last Saturday we can cope with that physicality. England didn't finish off their chances, so we've got to cut the line-breaks out that were made against us.
"We've got the players to win big games, though, and the boys will definitely go into Saturday's match against Argentina with a lot of confidence."
Wales finalise their World Cup preparations with a warm-up match against Argentina at the Millennium Stadium on Saturday.