Blackwell has loved the whole Under 20s experience, and this is his most intense rugby since he captained the championship-winning Wellington College First XV to the Wellington schools title in 2013 and represented the New Zealand Barbarians Schools.
"We've been building through the three games. Some of it has been top quality rugby but we have struggled a bit in some of it and been put under the pump. This week it's been about bringing everything together at training so we can put pressure on the opposition for the full 80 minutes," says Blackwell.
The breakdown is an "ongoing focus", he says. The retention of ball has been sloppy at times for New Zealand.
"I haven't played too much knockout rugby, but the energy is there and everyone will be ready for tomorrow."
Water breaks every 20 minutes have helped alleviate the hot weather, which has seen temperatures hit the mid-30s, a far cry from the depths of the New Zealand winter.
Robertson has been suitably impressed by Blackwell's output in the tournament.
"James is our lineout caller, a really good leader and understands what we are trying to execute on the field," says Robertson.
"We just want a performance that gets us into the final. We haven't collectively put in 80 minutes yet, but we have won the tight battles. We are growing knowledge in how we play different styles and situations. Part of our job (as coaches) is to educate and teach these young men in those areas."
New Zealand have scored some classic tries through their firepower in the loose forwards, where Akira Ioane is always dangerous on the fringes, and out wide where Tevita Li has scored three tries to go with his seven from the 2014 tournament.
"Since November we've talked about key moments. We'll have the passion and the skill. Now it's about taking our opportunities," says Robertson.
Magne has full respect for the New Zealanders, and almost played down his side's chances, though that won't fool Robertson and his offsider Leon MacDonald.
"They're a difficult team to play against as they really master their rugby and are very good on attack, and against a team that attack very, very well it's always very difficult," says Magne.
"They're a team with a lot of very good players, technically very good and players with talent who go very, very fast... they're a team who play total rugby and when you have a team that play total rugby it's always very difficult to win these match-ups."
Kickoff is at 4.30am tomorrow from Calvisano's Stadio San Michele, followed by defending champions England against 2012 champions South Africa.
New Zealand: Mitch Hunt, Jack Goodhue, Anton Lienert-Brown, TJ Faiane, Tevita Li, Otere Black, Te Toiroa Tahuriorangi, Akira Ioane, Blake Gibson, James Blackwell, Hamish Dalzell, Josh Goodhue, Atu Moli (c), Liam Polwart, Ricky Riccitelli
Reserves: Steven Misa, Isi Tu'ungafasi, Tau Koloamatangi, Mitch Dunshea, Henry Stowers, Harrison Levien, Vince Aso, George Bridge
Road to the semifinals:
New Zealand
beat Scotland 68-10
beat Argentina 32-29
beat Ireland 25-3
France
beat Wales 19-10
beat Japan 47-7
beat England 30-18
