A taxing series of scrums in the second quarter did not so much sap the strength of the Welsh pack as suck out their very lifeblood. Each colossal shove on the Argentine ball or on a Welsh put-in drew a collective groan from the crowd, all of who flinched in sympathy every time the Pumas put the squeeze on the scarlet-shirted Dragons.
It was no surprise that, as the half progressed and Wales conceded a string of penalties, the Argentines opted for the scrum each time. Every one of them a painful experience. Twice they snatched tries from them and Welsh heads, when they were not popping up at the set piece, began to drop.
They had begun the match conceding a total of more than 4st to the South Americans. When the talismanic Scott Quinnell - at 20st the heaviest man on the field - was forced to limp out of the fray shortly after the interval to be replaced by Mike Voyle they lost a further 3st plus.
And yet it had begun so promisingly. The Dragons came out not merely breathing fire but blasting it in the faces of their opponents. The Argentines were given no time to think. The influence of their coach Graham Henry was evident from the first Welsh line-out.
The Pumas lined up. Wales waited and waited then suddenly a few forwards ran. Wales were left with fewer men than the Argentines in the line-out. The South Americans looked around deciding who should drop out and as they reduced their number so the throw was made and taken. That ploy paid off on a number of occasions.
In the loose Wales were rampant, with their forwards - no lumbering giants - repeatedly coming on to the ball at pace. The Quinnells, Scott and Craig, and Colin Charvis were immense, driving over the hard yards and smashing holes in the defence, creating openings which the backs were well able to exploit.
For more than half an hour a packed Stradey Park enjoyed the sight of the Dragons rampant. Then the troubles began. Wales began conceding scrummage after scrummage. The tighter the game got the closer the scoreline became.
There was only a point in it at half-time and if it had been a boxing bout that would probably have been the margin. It needed the Welsh to rethink and play their own game after the interval.
The loss of the elder Quinnell did as much to fire them again and with Scott Gibbs in the centre battering his way through like a forward time and again it sparked the big men up front into life. But the Argentines had made big inroads into the Welsh reserves and heroic efforts were needed. And they were made as the home side held out and lifted siege after siege. After their experiences last night it will not be a surprise if they need counselling to talk out the trauma of locking horns with a herd of monster Pampas Bulls.