"Probably they're not but I don't think it is worrying them too much," he said. "I think it's basically because Canterbury were so dominant for so long and everyone at the start of the season were picking Canterbury to win it and the Chiefs without Sonny Bill would be no good and all of that."
Sir Colin said a Chiefs win on Saturday would be "huge" for the franchise.
"If they win this one they will get huge publicity and huge raps for it so I think this is the big one for them.
"To win two in a row is quite an achievement - they're capable of it if they put another game together like they did on Saturday."
His sentiments were backed by former All Black midfielder and Chiefs stalwart Matthew Cooper, who said many in New Zealand had "collective amnesia", forgetting the side's consistency and results.
While stopping short of saying there had been a power shift north from the Crusaders, Cooper said the Chiefs coaching staff and management had created a new legacy.
"A lot of the country don't realise what has gone in behind the scenes and you can talk about character, you can talk about belief and attitude. It's certainly a foundation on which the Crusaders have built their legacy but now I think everyone knows that there's another legacy that has developed in New Zealand rugby.
"I think you have two franchises that have quite a bit of a gap on the other three and the Chiefs are quite deservedly at the moment ahead on points on the Crusaders."
Chiefs chief executive Gary Dawson said his side had been written off in several quarters before the Crusaders match.
"The guys had played well and put in a huge amount of work leading into the Crusaders match - a lot of the so-called experts had written us off and they were proven to be wrong.
"I hope the coaches and the players get the respect that they deserve."
Tickets went on sale for Chiefs season ticket-holders on Sunday and the franchise's commercial manager, Sean Austin, said 6000 had already been sold.
The Brumbies have a strong record against the Chiefs, winning 11 of their 18 clashes with four in New Zealand.
The numbers
8am tomorrow tickets go on sale
6000 tickets have already been sold to Chiefs season ticket holders
11 of the 18 clashes between the two teams have been won by the Brumbies
4 of those victories were in New Zealand