Why Ireland are better prepared for World Cup quarter-final this time round, explains key man Johnny Sexton
Four years ago, as Ireland prepared to face Argentina in the World Cup quarter-finals, the physical toll of reaching that point was there for all to see.
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Having already lost their starting outside centre, Jared Payne, to injury, the pool-clinching game with France came at a heavy cost.
Gone was the captain Paul O'Connell, never to pull on a green jersey again. Also invalided out of the game against the Pumas would be Peter O'Mahony and Johnny Sexton, while Sean O'Brien was to be banned later in the week.
The All Blacks had been avoided, but at what cost?
This time around, at the conclusion of the pool stages, Joe Schmidt's men couldn't extricate themselves from a collision with the world champions but the toll in getting here seems considerably less too.
A considerable but not fatal blow was dealt by Japan, the lead-in giving enough time to finally shake the hangover that lingered into the win over Russia five days later.
Not only is the squad in considerably ruder health, but the mental energy expended in the last week has been a notch below 2015 as well.
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Where the victory over Les Bleus ended with Ian Madigan, on for an injured Sexton at No.10, pumping his fist as tears rolled down his cheeks, against Samoa on Sunday it was a case of handshakes and onto the next job.
"You saw the difference in celebration between the last World Cup and this one," noted Sexton.
"I suppose the French game was just the big game in that pool and it was the last game and then with the atmosphere and the stadium we were in, it was almost like a comedown for the Argentina game.
"It was very emotional after the last World Cup, winning the pool game, whereas I think we're just business as usual.
"This is where we always wanted to get to, where we feel that this is the little bit of history that we can make, getting Ireland into their first ever semi-final and then we can re-evaluate after that.
"Like I said, this is where we wanted to be and we knew, New Zealand or South Africa, for us it was much the same. They pose different challenges but they're both world-class teams and we knew either fixture was going to be really tough. This is the one we've got and we've got to roll with it now."
For Sexton, even for all he's achieved over a stellar career, this is the game of a lifetime. At his first World Cup it was Ronan O'Gara who started the last-eight tie. That injury four years ago means it's been a much longer than anticipated wait to have the 10 jersey to himself on this stage.
"I think at the start of the week, I remember getting a scan and the scan said it was relatively clear and you kind of bluff yourself into thinking, 'This is okay' and I remember doing the captain's run, I think it was two days before the game, and it just wasn't right. I went for another scan and the injury showed up.
"I was doing everything possible to try and get in and get on the pitch. It just wasn't to be.
"I've had disappointments, that I've missed out on those big days, like you do when you miss out on any big day. They're just regrets over watching the games, so hopefully I can get out there on the big stage and put in a big performance."
Ireland will need him to. One of the supposed lessons from that Argentina defeat was the folly of being so reliant on one player, no matter how special the player, in a sport where the injury toll is so high.
While efforts were made, and the previous injury to Joey Carbery unfortunate, that feels likely Andy Farrell's problem now. It's likely no coincidence that Schmidt's key player being on the pitch has again coincided with their best rugby in Japan. Absent for the loss against the hosts, the game against Russia became a slog only after his half-time departure while he pulled the strings against Scotland and Samoa until both were beaten. Once again the situation is simple, Ireland will go as far in this tournament as Sexton takes them.
For his part, a man who has won everything there is to win at Leinster, and played in two series-deciding Tests for the Lions, believes this is the biggest game of his career.
"It's the biggest (challenge) and in that regard then, it is the most exciting," he said. "We said it after Samoa, we said, 'Look lads, no matter who we play, this is the biggest game of our lives'.
"You feel it straight away. You feel it when you wake up this morning and your mind just goes straight to the game. So sleep will probably be a challenge this week.
"It's where you want to be as a kid watching. I think my first memory of watching Ireland in the World Cup was against in New Zealand (in 1995).
"It's where you want to be and it's where you want to challenge yourself, it's where we can create something a little bit special back in Ireland. I am sure the country will go mad on Saturday morning, so I can't wait for it."
Oct 19: England v Australia (Oita, 8.15am)
Oct 19: New Zealand v Ireland (Tokyo, 11.15am)
Oct 20: Wales v France (Oita, 8.15am)
Oct 20: Japan v South Africa (Tokyo, 9am)
Oct 26: Winner QF1 v Winner QF2 (Yokohama, 9am)
Oct 28: Winner QF3 v Winner QF4 (Yokohama, 9am)
Third-place play-off November 1, Tokyo 9am
Final November 2, Yokohama 9am