He and his wife Margaret watched all of the 116-test veteran's 80 minutes as he led senior club side Christchurch to a 22-5 victory over University at Christchurch Park.
It was a rusty start for the international star. An early dropped pass drew a collective groan from the 2,000-strong crowd.
He stood hunched, hands on hips, puffing hard at lineouts. But as the match wore on and the pitch became increasingly boggy, a slimline McCaw started to make his mark.
He carried the ball strongly, cleared lineout ball, swept rucks, and organised defensive lines.
Early in the second half, University second five-eighth Hamish Catherwood found out why McCaw is feared by the Springboks and Wallabies as McCaw steamrolled into him and crash-tackled him to the ground.
Catherwood looked dazed, shook his head, before getting up and slapping McCaw on the back in recognition of a magnificent tackle.
After the match, with a bloodied nostril and grazed face, McCaw admitted to being "pretty rusty", but was glad to "get it under the belt".
"In the second half I definitely started to get the feel of it until I started to run out of gas a bit."
Now he hopes to rejoin the Crusaders for their crunch Super Rugby playoff match next weekend.
Coach Todd Blackadder, who watched the last 30 minutes of the match, along with several Crusaders, said they'll decide in the next few days.
"He looked a bit knackered but he'll know if he's ready."
McCaw snr agreed.
"There was a bit of huffing and puffing but he seemed to survive. I think he'll be pretty happy. They won - that's the main thing."