The most capped flanker in world rugby, and two-times World Cup-winning captain in 2011 and 2015, told the All Blacks Podcast powered by SAP, he was often asked which was his most memorable Test.
It was a difficult question to answer because of the different games, such as winning tournaments and the like, but in the final analysis, the one that sat ahead of the rest was the day he became an All Black.
"It's where the dream of growing up becomes a reality, and once you've put that jersey on, no one can ever take that away from you again. So, that's why I say that was the most special time.
"And, I always add on my last game in 2015 where we won the World Cup, and I still felt like I was playing as good as I had any other day that I'd played," he said.
His Test selection after his introduction to both NPC for Canterbury and Super Rugby for the Crusaders was minimal in his first seasons in 2000 and 2001, respectively. But the NPC campaign in 2001 saw him play most of the Canterbury campaign among many All Blacks who played some memorable rugby.
"Steve Hansen had just taken over as coach and we adapted or changed a little bit how we were playing, and using the ball a lot more suited our team. I guess being able to slot in there besides some pretty established All Blacks was exciting, and because we managed to win that competition it was easy to play well," he said.
All Blacks selection resulted at the end of the NPC. Because of a change in coaches mid-season, there was an air of expectancy around how the new coaches, John Mitchell and Robbie Deans, might shape their side.
Josh Kronfeld had retired 12 months earlier, Taine Randall had played some games on the open side of the scrum, and Marty Holah had played as well, but no one had a firm grip on the flanker's No7 jersey.
McCaw said his name had come up in pre-tour fan speculation although he had no indication, and it was while listening to the radio at some friends of his parents that he learned he had the call-up.
While taking part in the All Black pre-tour initiations of distribution of new apparel and team photos, he was aware that until he got on the field, misfortune could deny him the chance to be an All Black.
Once he received his Test jersey in Dublin from manager Andrew Martin, the first thing he did back in his room was put it on, and then the thoughts started about whether he was up to the task.
He found it helpful that fellow Canterbury loose forwards Reuben Thorne and Scott Robertson were with him making his Test debut a little more comfortable.
"I didn't want to be a one-Test All Black, two Tests, and then it was realised you were not up to it, and someone else would get a crack.
"I was desperate to show that I belonged. But I didn't know what to expect. I didn't know how to play a Test match.
"I was sort of 'how's this going to go, what's it all about?' and people say 'Oh, it just goes like that and everything's quicker and faster, and more physical,'" he said.
Then, on the Friday before the Ireland Test in Dublin, Mitchell took him aside and asked him how he was feeling? McCaw said he was ok.
Mitchell said he would be a bit anxious but told McCaw he had picked him because he was the best in the country.
"I said, 'Oh, ok, thanks man, it's pretty cool' and he said 'Just go out and do what you've been doing,'" he said.
That relaxed him, but did not eliminate game-day nerves.
Reflecting on the game 21 years later, he said the level of analysis of opponents was not the same as in recent times. He knew the names of players he would be playing, but was more focused on what he needed to do regardless of who he played.
He remembered when Andrew Mehrtens kicked the ball to start the game that when he ran after it, he thought, 'At least I'm an All Black now'. He also remembered dropping the first pass he received, and it was 20 minutes before he started to get into the game.
Early in the second half, after Ireland scored, the All Blacks were down 7-21, but from a scrum soon after, wing Jonah Lomu scored, and McCaw marvelled at how easily it happened. And it turned the game.
"Up until that point it had been a good old wrestle," he said.
The All Blacks went on to win 40-29, and McCaw was named player of the match on his debut.
He said there was a lineout a minute or two from the end when they named the player of the day, and he thought to himself, 'That might have been my name.' And while that was special, receiving his Test cap at the post-match dinner was more memorable.
McCaw said he had a lot of time for the Irish, their rugby and their way of life. That was encapsulated in opposite number David Wallace's gesture of giving him his jersey after the game, but understanding that McCaw was reluctant to part with his first Test jersey.
"I thought that was pretty cool," he said.
McCaw also learned after another few visits to Ireland of the way rugby unites Ireland and Northern Ireland and felt that was a powerful reflection of what sport can achieve.
The history that divides the island was seen in Belfast when visiting Falls Road and Shankill Road and when playing the first rugby Test at Croke Park, the home of Gaelic Football, in Dublin, while Lansdowne Road was redeveloped.