Covid-19 issues have forced a change in fixtures after the Wallabies beat the closing of the Tasman travel bubble when given an economic exemption to travel to Auckland from Queensland.
The plan had been to play the opening Test in Auckland, travel to play the second Test in Perth and then return to Wellington to complete the series.
However, the changes saw the Wellington Test scrapped, the second Test moved to Auckland, with the final Test now in Perth.
But McKellar said ahead of the first Test on Saturday, "Two Bledisloes in a great stadium and atmosphere, big crowd is why you play and coach. We're all excited for the challenge."
As coach of the Brumbies, McKellar had a good look at the talent on show for the All Blacks when his side played their first three games in the trans-Tasman Super Rugby competition this year in New Zealand.
The All Blacks were human, he said. While it might not always be obvious, they were vulnerable to pressure that could result in mistakes.
They had threats across the park. They would challenge the Wallabies' set-piece, and they would challenge on turnover attack.
"From an unstructured scenarios, we need to make sure that we defend well," he said.
"They have quality players, but the big thing is, they're human beings and if you put them under pressure, put a little bit of stress on them, we saw last year through Wallaby performances they can feel that stress, pressure and anxiety and [we can] cash in off the back of them.
"We've got a whole lot of respect for them. We've focused on what we've learnt from the French series and understand that we need to front up in a couple of key areas to win our first game," he said.
McKellar also confirmed that next season would be his last with the Brumbies. He will leave Canberra and return to his Queensland home to concentrate on his role with the Wallabies.
"It'll be a sad day to get back there once I finish my commitments here, and rip in and have a really good season to finish off my time there.
"The timing was right for me and my family. I've got two young girls and a wife who have been incredibly supportive, and it's probably time for them to go home, back to Queensland. It's time for me to challenge myself and coach at the highest level with the Wallabies," he said.
The decision was tough because he had loved being involved in Canberra and working with the people at the Brumbies.
"I've got a lot of good memories there and I hope we can create a few more next year," he said.