"I don't know that you'll see the same XV [for every match]. We just can't do that, we don't think. You might see the same 10 or 12 on a regular basis."
That means key players such as captain Richie McCaw and Dan Carter will start the majority of matches - including pool games - as will Brad Thorn and Owen Franks.
All four Crusaders were rested during the Tri-Nations following an arduous Super Rugby season which, as Hansen said, probably contributed to their defeat to the Wallabies.
There are still some selection puzzles for the selectors but they are mainly confined to the backline. Mils Muliaina clearly has experience but is in danger of being overtaken by Israel Dagg, who has made a spectacular return from a serious thigh injury.
"Dagg played fantastically well in South Africa," Hansen said. "Mils has played 98 tests and it's hard to find many that weren't top performances. That's a pleasing contest we have there and I'm sure Mils will stand up to that contest and I'm sure so will Israel."
Another is on the wing where Richard Kahui could have a claim following less than convincing performances from Zac Guildford and Cory Jane recently.
In the forwards, Tony Woodcock's inclusion for the Tonga match could be in doubt due to a hamstring twinge and Thorn's locking partner could be either Sam Whitelock or Ali Williams.
Williams made a good impact when coming off the bench against Australia in Brisbane, with Whitelock having the inside running as starting lock. But Whitelock could also play a role as a reserve due to his ability to cover blindside flanker, a potential problem area given the injuries to Kieran Read and Adam Thomson.
Now that the tournament is finally about to start, Hansen admitted to some excitement.
"Not only is it a World Cup, it's a World Cup in New Zealand," he said. "We can't wait for it to start.
"Playing Tonga in Auckland, where there is a massive Tongan population, is going to be quite special."