McCullum confirmed today that he will also open the batting in the absence of the injured Peter Fulton.
"Peter was going to open but he has been struck down by an injury. That gives an opportunity to Dean Brownlie," McCullum said.
"I'll come back to the top of the order and Dean will come in at four. I've been opening the batting for the last little while and you've got to bat at some point," he said of the challenge of facing South Africa's formidable pace trio of Dale Steyn, Vernon Philander and Morne Morkel.
Told that Philander had passed a fitness test after being a doubtful starter because of a hamstring injury, McCullum said: "He's an excellent bowler. His stats have been phenomenal but from our point of view we're playing against a very good cricket team so we expect them to have very good cricketers in their side."
New Zealand's three leading batsmen will fill the first three positions in the order. Martin Guptill will open with McCullum, while Kane Williamson will bat at three.
"Martin's been in good form and hopefully we can establish a pretty good partnership up front," McCullum said.
He praised Williamson, who scored a century in the final Test against South Africa in Wellington last year, as one of New Zealand's up and coming stars.
"He's got a lot of cricket intelligence for a young guy. He's popular in the team and he works hard on his game. He ticks a lot of boxes and we're hopeful that he's going to have a big series."
McCullum acknowledged that his team had a difficult task with a side weakened by injuries to several players and the absence of former captain Ross Taylor, who withdrew from the tour.
"It's a huge challenge but with that challenge comes a great opportunity to play against a very good cricket team, the No 1 team in the world. That's why you play the game," he said.
"If we can look back and say we've done a very good job and put them under pressure this can be a catalyst for long-term performances for us a cricket team."
South Africa, meanwhile, are determined to consolidate their position as the world's top Test side.
Graeme Smith, their captain, said South Africa were eager to get into action in their first home match since taking the No 1 ranking during an unbeaten run of nine Test matches on foreign soil.
"The team has taken big steps forward in 2012," Graeme Smith, their captain, said. "We've travelled a lot in the last year. It was hostile, it was tough. Hopefully now we can play the same style of cricket in South Africa with home support."
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