McCaw lines up alongside eight Springbok tourists for the Barbarians against Australia at Wembley this evening and the 27-year-old feels results this autumn make the outcome of next year's tour easy to predict.
"I suppose if you go on what has happened in the autumn you could pick the result pretty easily," says McCaw who was hugely influential in the Lions' downfall three years ago.
"We played them back in 2005 and I am sure there are a few lessons learned from that trip. It is not easy for those guys to come and play at the end of a long, hard season.
"And given that John Smit is my room-mate with the Barbarians I have no choice but to say South Africa!"
Tonight's match will be McCaw's first appearance for the Barbarians and he is unsurprisingly looking forward to experiencing the unique atmosphere associated with the invitational XV.
"Normally we don't see each other after games, we have to just move on, so being able to sit and have a beer and a yarn without worrying about the pressures of next week is unique," added McCaw.
"Rooming with guys you normally beat the hell out of - or vice versa - is pretty good. And John is a good roomie - his snoring was all right last night!"