What's more, come Tuesday night, when Ireland come face to face with the pre-tournament favourites, it is highly likely that Rennie will wheel out 137 kilogramme tight head Ben Afeaki and 130 kilogramme loose head Rodney Ah You.
Work it out for yourself. With hooker Quentin Macdonald (100kg) as the meat in the sandwich, that's close on 60 stones of front row forward coming at you. Ouch!
Rennie, who led his side to last year's Under 19 World Championship in Belfast, said: "There are some big guys in the squad, but they are very talented too.
"They have worked hard for their clubs and some of them in the Air New Zealand Cup and even the Super 14s this season. Yet they come here fresh and will be looking to emulate the success of the under 19s last summer."
Amongst the names to look out for over the coming weeks are Crusaders' trio Sean Maitland, Masi Manu and Kade Poki - all of whom featured in the Super 14 final success against New South Wales Warratahs last weekend - and Zach Guildford, who became the youngest player to pull on a senior Hurricanes jersey when he featured for the Wellington based province last year.
It adds up to a formidable unit and one which will certainly test the other three nations in the pool - Tonga, Argentina and Ireland, who are led by the outstanding young back row forward from Blackrock, Paul Ryan.
A Leinsterman with pace to burn and plenty of experience too, Ryan said: "We couldn't have been dealt a much tougher hand in terms of our Pool, but we have prepared well and feel in good shape going into our first game.
"As long as we achieve our potential and perform to the best of our ability, I can't ask for anymore from the boys."
Opening up against the Pumas tomorrow (Friday, 7.00pm), Ireland will hope to go one better than their under 21 side did at the World Championship in Clermont Ferrand two years ago when, despite putting up a brave show and out-thinking their opponents for much of the game, the brute strength of the Pumas earned them a 26-22 victory.
It promises to be another bruising battle this time, although a decent Six Nations campaign in which they might have finished higher than fourth had they have enjoyed the rub of the green against Wales, should hold them in good stead.
Other Pool A matches:
Tuesday June 10
7.00pm Argentina v Tonga
9.10pm New Zealand v Ireland
Saturday June 14
3.00pm Ireland v Tonga
5.00pm New Zealand v Argentina
Match tickets are on sale at £2 for children and £8 for adults and can be bought at the Arms Park Ticket Office right up until kick-off.
New Zealand: Zac Guildford, Joe Hill, Michael Harris, Jackson Willison, Andre Taylor; Daniel Kirkpatrick, Aaron Smith; Paea Fa'anunu, Ash Dixon, Toby Smith, Chris Smith (Capt), Josh Townsend, Peter Saili, Hugh Reed, Matt Luamanu
Replacements: Quentin MacDonald, Sam Whitelock, Ben Afeaki, Luke Braid, Grayson Hart, Trent Renata, Ryan Crotty
Tonga: Sione Toke; Mateo Malupo, William Takai, Charles Mateo, Salesi Sete; Richard Kaufusi (Capt), Mahe Fangupo; Mosa'ati Afu, Tone Tukufuka, Maleko Latu, Sotele Hehea, Finau Tupa, Constantin Kauvaka, Paula Kata, Inoke Taufa
Replacements: Lepaola Taueli, Lonely Kengike, Tevita Tangi, Haloti Molitika, Samiuela Vea, Sekope Maea, Alfred Hausia
Argentina: Joaquin Tucullet; Belisario Agulla, Juan Pablo Estelles, Juan Pablo Socino, Diego Palma; Benjamín Madero, Martín Landajo; Mauricio Guidone, Esteban Bustillo, Juan Figallo, Guido Lofiego, Santiago Guzmán, Ignacio Pasman, Lisandro Ahualli de Chazal (Capt), Francisco Panessi
Replacements: Luciano Leibson, Ignacio di Santi, Guillermo Roan, Marcos Insúa, Lucas Alcácer Mackinlay, Nicolás Sanchez, Federico Salazar
Ireland: Niall Morris; Sean Scanlon, Eoin O'Malley, Conor Cleary, Chris Cochrane; Martin Dufficy, David Moore; Paul Karayiannis, Jason Harris-Wright, Ben Barclay, James Sandford, Eoin Sheriff, Kieran Essex, Paul Ryan (Capt), Patrick Mallon
Replacements: Stephen Douglas, Stephen Archer, Ian Nagle, Michael Entwistle, Ian Porter, Ian Madigan, Eamonn Sheridan