Lomu, who had burst onto the world scene at the 1995 Rugby World Cup in South Africa, had reinforced his reputation with dynamic play at the 1999 World Cup in England while battling a chronic kidney condition. He was rugby's first global phenomenon.
McCaw said he first played against Lomu in a Canterbury-Wellington Ranfurly Shield match.
He had watched Lomu play on television while a schoolboy and thought it should be a case of tackling him around the ankles to knock him over.
McCaw said on the All Blacks Podcast powered by SAP: "I had two goes at tackling him that day and both times I didn't go so good," he said.
But touring on the same side with him in Europe, Britain and Ireland, he learnt the star factor Lomu enjoyed among the local fans.
"He was just huge with a massive following," he said.
In Ireland, he experienced the interest in Lomu first-hand.
"I remember one of the trainings we went to, we got off the bus, and there was a heap of people who knew we were training and, as I was walking towards the ground, a huge crowd came running at me, and I was like, 'this is pretty cool'.
"And they just kept going past. I turned around and it was Jonah walking behind me. He just got mobbed everywhere he went," he said.
Later in the tour, in Argentina, in the third Test, when things were not going well, Lomu scored a try from nowhere. He was the difference for the All Blacks.
McCaw said it was sad he couldn't play to his full potential due to his sickness.
"He could have been even better than what we saw," he said.
"It was always about the jersey and the team being ahead of him and that's something I admired. He never complained."