At stake is an historic first appearance in the World Cup final with neither side having progressed past the semis in the past.
New Zealand were forced to hastily rearrange their squad on Monday after Adam Milne was ruled out with a left heel injury and Matt Henry was rushed up to Auckland.
But McCullum said they remained confident without their express bowler and the presence of Guptill after his colossal 237 not out against West Indies was an inspiration to the rest of the team.
New Zealand have won four of their six previous World Cup clashes against South Africa, including the last three, but McCullum said history had no bearing on this battle for the right to play the winner of the second semi between India and Australia, taking place in Sydney on Thursday.
Much more relevant was the boost to his side of Guptill’s return to form. “To see it in such a crunch game as well and still display the same game plan which he trained so hard for was confirmation that obviously it can be done and that will flow on in terms of confidence for the rest of the squad,” he said.
Guptill came into the tournament with a string of disappointing scores including two golden ducks against Sri Lanka but has progressively played his way into form. His last three innings have been 57, 105 and 237 and McCullum expected more.
“The game throws up its ups and its downs but you need to be able to remain reasonably level and go about your work.”
The way that ‘Gup’ was able to back up a really good hundred against Bangladesh and then to be able to turn in such an amazing performance as he did the other day shows that he certainly possesses those characteristics.
“He’s been a huge player for us in this tournament and I’d suggest he’s probably not quite done yet.”
