Some of the previously optimistic Irish fans who had bought tickets for the semi-finals made the trek to Twickenham over the weekend.

There were clearly more who had envisaged Ireland advancing as Pool D winners and negotiating the Pumas judging by the greater spread of green jerseys, tricolours and green wigs at Sunday’s second semi-final.

Ultimately, one ventures they enjoyed what must have been a first taste of the Rugby Championship coming to Europe.

Having trimmed the Rugby Championship to prepare for the World Cup, the Southern Hemisphere have taken their final round to London. And it’s been cracking stuff so far, with more to come in the shape of Friday’s third place play-off between the Boks and the Pumas, followed by a meeting between the two countries from either side of the ditch, New Zealand and Australia.

It blew a few myths too. Great rugby matches can take place in the rain too. In that regard, Saturday's first semi-final had a distinct whiff of the Six Nations about it, what with the rain and plenty of kicking out of hand, but with a distinctive Southern Hemisphere twist, before and during the All Blacks' epic arm wrestle with their old foes from South Africa.

As Warren Gatland has occasionally remarked in these pages, supporters from the rival Southern Hemisphere countries do not travel to away games in the numbers akin to the Six Nations due to the greater distances between the countries.

Amazed many pundits

So that made the mix of Blacks and Boks supporters amongst the 80,000 crowd probably the best which this fixture has ever have known. What really amazed many pundits was the apparently greater volume wearing black given the number of South Africans living in London. There must have been 30,000-40,000 New Zealand supporters in the crowd.

Television can never properly convey horribly wet conditions on the day. The second half especially was played in an almost constant downpour, and yet the moderate amount of handling errors was testimony to the superior skills-set of the Southern Hemisphere giants.

Akin to England's volte face at the first whiff of danger when Wales loomed after their opening win over Fiji, the Springboks abandoned the expansive running game developed under Heyneke Meyer over the last two years when rocked to their socks by Japan.

The difference was that the Boks not only reverted to type, but to traditional virtues.

Akin to their triumph in the 1995 final, their scrum, lineout, maul and big aggressive defence, coupled with Handré Pollard’s unwavering radar, was almost enough. The variety that they brought to semi-final weekend was no bad thing, for all sports need variety.

It would be a boring old game if everyone played the same, but justice was done. In maintaining their composure and utilising a more rounded game, the All Blacks underlined their status as the rainmasters.

Thankfully, the freakishly benevolent weather which has graced this tournament returned for Sunday’s second semi-final, which meant Argentina could bring their all-singing, all-dancing team and supporters to the party.

Even the presence of Diego Maradona (there were a few barely discernible boos) could not ultimately prevent the 'neutral' English et al adopting them as they irreverently had a go from anywhere.

But typical of a Michael Cheika team, Australia were way too streetwise, physically committed, together and opportunistic.

Four tries to nil, and given how Argentina’s mesmerising footwork and angles of running pierced their initial line of defence 13 times, the ‘nil’ part was as impressive as the ‘four’.

Yet it was fun while it lasted. The Pumas have been revitalised by the revolution under the off-field direction of Agustín Pichet, Fabien Galthie, Graham Henry and the not-for-turning Daniel Hourcade in the last six years. It shows how anything is possible with the right direction.

European order

The old European order did them a favour by declining their request to join an expanded Six Nations after the 2007 World Cup. They have progressed more in the last four years than they would have over eight in the Northern Hemisphere.

It was sad to see the ridiculously gifted Juan Martín Hernández hobble off, and most probably their wonderful warrior Juan Martín Fernández Lobbe won’t be around for the next World Cup.

But their elusive duo of Joaquín Tuculet and Santiago Cordero, world-class finisher Juan Imhoff, the two locks Guido Petti and Tomás Lavanini, their potentially brilliant flanker Pablo Matera and number eight Facunda Isa, are all in their early 20s.

New arrival

And one imagines they and the rest of the Pumas’ next wave might learn another trick or two after playing New Zealand, South Africa and Australia home and away each year in the next World Cup cycle.

For all World Rugby’s talk of expanding the game – and the tier two countries have closed the gap at this World Cup – there hasn’t been a new arrival elbowing their way into the game’s long-established elite since France. And that was a while ago.

But Argentina are dining at the world’s top table and are here to stay as a major force in the game.

And so New Zealand and Australia will have a reprise of their World Cup finals in rugby league (the Kangaroos beating the Kiwis 34-2 in the 2013 decider, which was also hosted in England and Wales) and in cricket (Australia beating the Black Caps by seven wickets in the 2015 one-day final in Melbourne last March).

These Trans-Tasman rivals are hogging it a bit, but a third Australian victory really could be too much to bear for the Land of the Long White Cloud.

In any event, bring it on. This has been special.

gthornley@irishtimes.com