Coach Stephen Kearney would love to have Sonny Bill Williams in his 24-man squad in the UK and France, but he has a plethora of back-row options and is even reasonably well stocked in the halves - although he won't want to be without the ever-improving Kieran Foran.
It's at hooker where depth is still a little thin and where Luke is a cut above. Not only is he an 80-minute player, which impacts on the make-up of the interchange bench, but he is also acknowledged as the best dummy half runner in the game and a master at exploiting tired and lazy runners.
The 26-year-old was a player Australian coach Tim Sheens and captain Cameron Smith singled out for attention in this year's Anzac test, and his presence even helped shape the selection of the Kangaroos' side as Sheens opted for a mobile forward pack capable of containing Luke.
"I didn't know that until after the game," Luke says. "I knew then why they were throwing everything at me."
It wasn't something Luke or his teammates could overcome, as the Kiwis saw a good start unravel in a 32-12 defeat in Canberra but there's a growing belief they can once again push Australia at the World Cup.
Five years ago the Kiwis beat Australia 36-24 in the final to win their first world title. Luke played a leading hand in that, coming off the bench to kick three goals from three attempts and keep the pressure on with his darting runs.
He had made his international debut only months earlier as a 20-year-old in the 2008 Anzac test, which also marked the start of Kearney's reign as coach. One thing Kearney often said in that week about his young hooker was that he was cheeky. He can be a larger-than life personality, which teams often need, but it's something that has also got him in trouble on and off the field.
In 2011 he admitted he tried to break the leg of cousin Rangi Chase with a leg twist in New Zealand's 28-6 defeat to England because Chase turned his back on the New Zealand jersey and he was also widely slated for a cannonball tackle on Australian prop David Shillington earlier in the Four Nations.
Last year he was dropped by Rabbitohs coach Michael Maguire for breaking curfew while attending a family member's stag party and for an altercation with prop Scott Geddes at training. Luke now looks back on that time as "a good thing".
"When things don't go your way, you have a choice whether to drop your lip or get back on the horse," he says. "At the start I dropped my lip but then realised I needed to go backwards before I could go forwards. I wasn't happy at the time but, looking back, it was the kick up the arse I needed and it pushed me to do as well as I could.
"It's picking your times with that stuff. It's being able to have a laugh every now and then but you also need to know when to switch on.
"In the early days I look back at some of the things I did and think, 'I wish I hadn't done that'. I have matured as a player, especially since Madge (Maguire) got here. He makes sure he gets the best out of players, from Greg Inglis down to the youngest player."
The Rabbitohs have built a formidable side under Maguire - as well as co-owner Russell Crowe's millions - and there are genuine hopes around Redfern they might be able to deliver their first premiership since 1971.
Luke is one of a handful who remember what it was like to finish nearer the bottom of the table. He was scouted by the Bulldogs in 2004 as a precocious fullback or winger but picked up by the Rabbitohs in 2006 and converted into a hooker. He made his NRL debut in 2007 and they made the finals only once in his first five seasons.
"The early days were hard," he remembers. "But it makes us appreciate what is going on now. It's something we can look back on and judge where we are at at the moment. Those were the years when we really struggled.
"We can't jump out and say anything at the moment because we haven't achieved anything yet. The club's got a pretty proud history and, as a group, we want to hold onto that legacy and create more memories."
Luke has been honoured by the Mid Central Zone, which includes the Hawkes Bay, Manawatu and his home province of Taranaki with the creation of the Issac Luke Cup, a tournament for the top high schools in the district.
Luke desperately wanted to attend but it clashed with his Rabbitohs commitments and he was instead represented by his grandparents.
"There are things in life you want to be part of and that was something," he says.
Another thing is just around the corner for an even more significant prize and Luke will be at that one.
Issac Luke
Age: 26
Position: Hooker
Club: Souths (144 games - eds - this takes into account Friday night's game)
Tests: 23 (debut 2008)
Luke hails from Hawera and was a member of the all-conquering Wellington under-18 side in 2004 that also contained Simon Mannering, Sika Manu and John Te Reo.
