Will the All Blacks' need for new centre options as Conrad Smith's career winds down play a part in Piutau wanting a change?
Jackson Willison, a good performer in the Blues midfield last year, will want game time too before he leaves for a new career at French club Grenoble at the end of the season.
Another new All Black, Frank Halai, is a lock-in for one wing, with George Moala and Albert Nikoro possibilities for the other. The rest of Kirwan's jigsaw remains in a state of flux.
While Marshall has been impressive during his time as playmaker in pre-season, Saturday's match could be a rude awakening. Kirwan has said there is no pressure on the 28-year-old, but it is entirely possible that after giving Marshall a taste of first-five, he prefers to have the cool head of Noakes at No10 for the season proper - injury permitting - or Baden Kerr, with Marshall continuing his education at fullback.
Nonu, meanwhile, has said he is pleased to be back at the Blues after his flirtation with the Highlanders last year turned sour.
"I'm pretty motivated, I'm really excited about the challenges ahead and I'm excited to be back in this group," he said in an interview published on the Blues website. "I had a bit of a tidy up in the off-season [on ankle], I'm starting to run hopefully in the next couple of weeks at full speed and I just want to get things right and don't want it injured again."
As for his reception from Blues supporters after his stint in Dunedin and generally wretched Super rugby form over the past few years, Nonu said: "I'm not sure [whether I'll be embraced by Blues fans], I hope so. I've just got to perform on the field."