There it was on the very first question time of Parliament, the Muhammad Ali question - the one that, when in the right hands, floats like a butterfly and stings like a bee.
And this time, it was in the right hands: those of Peters. Set down for the Prime Minister, it asked simply: "Does he have confidence in all his ministers?"
Government ministers were pale with fear.
For it is the Trojan horse of questions, the one that looks innocuous from the outside but is bristling with spears inside and gives no indication who it might impale.
Labour tried to use the question last term, but the impact was more of a sparkler than gelignite emitting a bit of a sulphurous smell but little bang.
However, National had made merry with the same question during its time in Opposition.
Key, while proficient at fending off attacks from Labour and the Greens, had never faced Peters in question time before.
Knowing the damage the question has caused in the past, the usual background gossiping and muttering died away when Peters stood to ask it in Parliament. The only sound was a slight whispering from the Government side that sounded suspiciously like the Hail Mary in stereo.
There was almost palpable relief from National when it was revealed that Peters' target was Maori Party co-leader Tariana Turia and her Whanau Ora scheme - set up to deliver social services to Maori.
Peters' claim was that the scheme was effectively funding its very own Missing Pieces programme, doling out money from a $6 million fund for what he described as glorified family reunions and what Turia describes as allowing whanau to reconnect so they can support themselves better, rather than rely on the state.
There is only one way to distract Peters when he is in this mood and that is to bring up his former transgressions.
Turia waved the red rag at the bull on Radio NZ yesterday, wondering how Peters could begrudge Maori families money to improve themselves when he was quite happy to take $158,000 of taxpayer funding for his 2005 campaign that fell outside the rules and not pay it back. Here, Turia was on much higher ground.
The Maori Party's bill from that year was a paltry $48, which it repaid immediately. Sure enough, Peters bit back, claiming that NZ First had given it to charities rather than back to the Parliamentary Service.
But Peters was not done, as yesterday's follow-up question indicated. That question was, "Does he still have confidence in all his ministers?"
So it begins: the first of the wasteful-spending headlines and at a time when the Government has taken such pride in trimming its jib and Turia has had to defend Whanau Ora against accusations that other agencies were losing funding to pay for her scheme.
Regardless of the defence Turia musters, the taxpayer-funded "grab a family reunion" will be what sticks.
Turia cannot afford to let the credibility of Whanau Ora be dented, and she knows it. Politically, it is the cornerstone of the Maori Party's relationship with National and the most commonly cited justification for the party's remaining in coalition.
It wasn't a killer blow, but slow drips erode even the hardest of rocks.
In the ecosystem of Parliament, the Maori Party is in danger of becoming the krill.
The co-leaders sit directly opposite the baleen whales of Peters and Mana leader Hone Harawira, both hellbent on doing them in, albeit for very different reasons.
National, meanwhile, can only hope that Peters' mission to depict Whanau Ora as a folly will divert his time and attention away from them.
It will not be able to rest at ease for long. NZ First has a parliamentary question every day.
Even if Labour doesn't buck up its act, Peters will happily wreak havoc with the confidence question.
And the more the cuts to the public service bite, the more Peters and Labour can put out the shingle as a safe house for leaks from peeved public servants.
Peters is also yet to exact revenge for the humiliation of being declared persona non grata by Key and then written off completely during Key's cup of tea with Act's John Banks.
It will be interesting to see whether Key can whip out one of his infamous elegant solutions when Peters sets about playing chicken with him.
