The sheer nerve. If Ireland were wanting to brandish their championship credentials, they did so with an extraordinary win at the death. For 70 minutes in the Parisian drizzle the game seemed to be meandering to a drab victory for Irish composure over French indiscipline, when suddenly France struck with a brilliant counterattacking try by Teddy Thomas, which seemed to have won the game.

The challenge had been set. Suddenly a point behind, when they had been cruising six clear for most of the match, Ireland had a little over five minutes to respond, but for a while, amid the shock of it, they were all fingers and thumbs.

The Stade de France was roaring, and all the more so when a big French scrum won a penalty. Anthony Belleau, the young fly-half on for his even younger colleague, Matthieu Jalibert, withdrawn in the first half with a knee injury, struck the long shot well, but it drifted wide. Ireland were still within range of a Johnny Sexton special.

Now with Munster-esque relentlessness, Ireland nigh on 40 phases through the rain without so much as a fumble. Such was the French defence, they merely crept forward to the 10-metre line, but it was enough. Forty-two seconds into the third minute of overtime, Sexton called for the ball. From 45 metres out he landed one of the boldest drop goals in Six Nations history to steal what ended up an outrageous win.

Not quite the 100-minute epic the last time the Six Nations was here but the overtime drama was not the only point of comparison with that infamous win over Wales.

Two of their promising half-backs, Jalibert and Antoine Dupont, were forced off with serious-looking knee injuries, the former on the half-hour, the latter just after France’s dramatic try, yet both were registered as head-injury assessments. The latter was particularly significant, as it allowed Maxime Machenaud to return in Dupont’s place for the last few minutes. Nigel Owens was clearly sceptical, as his touch judge, Wayne Barnes, had been last year when France worked the convenient reintroduction of Rabah Slimani into the fray under the most suspicious of circumstances. But the independent doctor, who hardly sounded convincing, confirmed to Owens the head injury was bona fide.

Teddy Thomas slaloms through to score what looked to be the match-winning try until Johnny Sexton’s intervention. Photograph: Thomas Samson/AFP/Getty Images

At the very least it was a curious development, but one quickly overwhelmed by the extraordinary denouement. The game had hardly deserved its final 12 and a half minutes. Ireland seemed comfortable throughout, their composure superior, even if they never looked much like scoring a try.

A display of rude muscularity by Jefferson Poirot scuppered one driven lineout, which was nevertheless threatening only for its proximity to the line. Otherwise, Ireland could never escape the grasping French hands, not to mention the pervasive wet. They were able to rely for their points on French indiscipline, which was spectacular at times. Sébastien Vahaamahina could not help himself, killing his own team with recklessness at the ruck time and again. Sexton collected his points with alacrity. When Guilhem Guirado, France’s phlegmatic captain of all people, coughed up one just past the hour, Sexton inexplicably scuffed the easy kick, the success of which would have rendered the late drama unnecessary.

France, though, were not without promise. Jalibert, alas, was lost to the game on the half-hour, his knee colliding with Bundee Aki’s, but Kevin Gourdon was magnificent and Virimi Vakatawa caused all sorts of problems. It was his mate on the other wing, though, who blew the game open.

Proceedings were meandering horribly, but, as is always possible with France, no matter how directionless and undisciplined they may seem, they bust into life in the 72nd minute.

From a quick throw-in, a nimble step and pass by Dupont did for Conor Murray and set Thomas free down the right, where he beat Rob Kearney, then cut inside to beat three more on the way to the line for a brilliant counterattacking score. The Stade de France thought that would be enough and all the more so when France’s scrum won that late penalty.

It would have been a vicious irony had the faultless Machenaud stepped up to take it but to Belleau fell the responsibility. His shot was wide, and Ireland had a chink, which is all champion teams need. Thus their ambition to prove one of those remains alive.