Just hours before that training ground accident in Wellington, McCaw had withdrawn from the All Blacks' last pool game against Canada because of ongoing soreness in his foot.
Earlier in the tournament he had missed what would have been his 100th test, against Japan in Hamilton, when he strained his right calf muscle.
McCaw has played against Tonga and France in the World Cup with all the focus now on his expected return for Sunday's quarter-final against Argentina at Eden Park. That side will be announced tomorrow.
The 30-year-old captain's foot troubles became public in February when he was diagnosed with a stress fracture in his right foot and had surgery to insert a screw in the fifth metatarsal.
He returned for the Crusaders in mid-April, lasted 30 minutes, then withdrew from the next match because of ongoing problems. The injury flared again towards the end of the Crusaders' campaign before McCaw played in the Super 15 semifinal win against the Stormers and the final against the Reds.
He played three straight tests against Fiji, the Springboks and Wallabies and was then rested from the side's trip to South Africa.
There were no more hints of repeat trouble until McCaw stood down last week against Canada.
'Whenever you have bits of metal put in your foot, there's a possibility of having these things," he said. "It is something I have managed all through the year. I got through training yesterday fine. I wanted to get ready for next week [the quarter-final against Argentina], that is why this decision has been made.
"I was pretty keen to play but with the knockout match I wanted to be ready to go. It was a bit frustrating but it is a niggle I have dealt with for a while."
Good buddy Ali Williams gave a buoyant report yesterday. "He went well, full training, I have given him a medical pass," the lock said.
Attempts to get a report on McCaw's metatarsal from the All Black medical team were unsuccessful.