You looked for nerves and expected them to make a show of themselves, while errors were also bound to provide a suitable accompaniment; yet neither proved barely visible.

Instead, Jonathan Sexton endorsed Declan Kidney’s eye-catching selection call with a pivotal performance which both illuminated a fog-choked Croke Park and gave sustenance to Ireland’s hopes for the future on a day which chilled to the bone.

The 24-year-old was by no means alone in delivering a big game to tame the Boks; Paul O’Connell was immense, Brian O’Driscoll again produced world class moments, while Rob Kearney, Donncha O’Callaghan, David Wallace and Jamie Heaslip were all huge contributors to Saturday’s win.

Yet Sexton still merits special attention as this was only his second game for Ireland.

What an impact, even if Kidney afterwards typically refused to be drawn into praising him.

While opposite number Morne Steyn was finding it difficult to bisect and probably even see the uprights, Sexton experienced no such problem and took up where he had left off against Fiji — when he impressively made all seven kicks at goal for 16 points on his debut — with four straight penalty successes before ending the day with a more than decent ratio of five from seven.

It proved enough to win this epic game, but his ability to land his kicks is only part of the package. Sexton can put huge distance on his line kicks as well and punished South Africa on several occasions.

His passing off either hand also looks to have brought a new element to Ireland’s running game — though we can forgive him once for ignoring an obvious pass to Heaslip with the number eight in space — while Sexton displayed that he can also tackle.

He certainly didn’t shirk his defensive responsibilities when helping nail marauding prop Tendai Mtawarira early on and also did a job on John Smit and Victor Matfield.

All big men and all put to ground.

If he didn’t realise it beforehand, Ronan O’Gara surely now knows that winning back the number 10 shirt is looking like a challenge which may only be weighted in his favour should Sexton succumb to injury.

Of course, we have to remember that as his name is now certainly inked in for Six Nations selection, the Leinster stand-off is still very much a rookie on the international stage and that there are bound to be difficult days ahead.

Even so, right here, right now, Sexton’s the real deal.