New Wallabies coach Ewen McKenzie has surprisingly thrust Toomua into the playmaking hot seat, leaving Quade Cooper to wait for his chance off the bench, and the All Blacks are making no secret of their intentions to make life as difficult as possible for the Test rookie.
Back for his first Test in almost nine months after a well-earned sabbatical, All Blacks captain Richie McCaw on Friday said the world champions needed to shut down Toomua to cut off Australia's ball supply to match-winning winger Israel Folau.
"I have been impressed with the way he led the Brumbies around the park," McCaw said after New Zealand's brief captain's run at ANZ Stadium.
"We have to make sure we don't allow him to do that. It's up to us to deny him time and good ball and put him under pressure. That's one of our jobs.
"Test rugby is different, but you look across the skills of those guys and there's no reason why they can't do a job if it's put on a plate for them."
Wallabies vice-captain Will Genia, who will partner Toomua in the halves, has no doubts the 23-year-old will handle himself in the Bledisloe cauldron.
"He's a very composed sort of guy," Genia said.
"He's been thrown the five-eighth jumper for his first Test against the All Blacks, but he's taken it in his stride throughout the week and I'll be expecting nothing less tomorrow."
Folau has enjoyed a spectacular first season in the code, bagging a tryscoring double on his Test debut against the British and Irish Lions before being crowned Australia's Super Rugby rookie of the year last week.
McCaw said the dual international must be contained.
"He's a skilful athlete. He's a big man. His skills under the high ball and what-not is pretty good but, again, if we don't give him much time to show those, hopefully we can limit his impact," McCaw said.
McCaw's only game time since New Zealand suffered a shock loss to England at Twickenham last November has been an 80-minute club match, two late bench appearances for the Crusaders and half a game against Canterbury in an All Blacks squad hitout last Friday.
Yet the ironman flanker was still preparing to last the full 80 minutes in his 118th Test match.
"I feel mentally in a good shape and I've done a lot of training," he said.
He admitted the All Blacks would miss destructive blindside flanker Liam Messam, a late scratching with a hamstring strain, and said the onus was on him and his replacement Steven Luatua to step up.
"The way he's played this year, especially with the Chiefs and what he did for us last year, he definitely brings a real physical edge and not having him there, I guess he's left a bit of a hole," McCaw said.
The All Blacks arrived an hour and a half late for their captain's run and only spent 20 minutes getting a feel for the stadium during a light run on match eve.
"We did a few lineouts in a gym nearby," McCaw said.
"We thought we would do it away from prying eyes."