The former Auckland Warriors and London Broncos half-back helped the Kiwis pull off one of the biggest upsets in sporting history with a 34-20 victory over defending champions Australia at Brisbane's Suncorp Stadium.
Leuluai played in all five of New Zealand's matches but, like his Super League colleagues in the England team, admits he struggled to adapt to the game in Australia, where the ruck speed is slower and teams adopt a more negative style of play.
"I thought I should have lost my place," he said. "I was struggling.
"To be honest I found it difficult and I think the English found that out. The standard is a bit different, it's definitely another level.
"It's a different style of game. You've got to complete sets and play a bit more structured. In England you throw the ball around a bit.
"It took me a while to get going, to get used to things, and I'm just glad I could put in a couple of performances to give back to the boys who have been putting it in all tournament."
Leuluai was switched to hooker on the advice of assistant coach Wayne Bennett, the former Kangaroos boss.
"Wayne knew I could provide something to the team," he said. "I think the move to hooker sort of took a bit of the pressure off.
"It was a supporting role I suppose but I've done my bit. That's what it's about, everyone doing their bit."
The bookmakers were offering odds of 7-1 against New Zealand pulling off a shock but Leuluai says the Kiwis coaches got their tactics right and the players stuck to the plan.
"We talked all week about not letting Australia be the big brother, about standing up to them," he said.
"You've got to give it up to Steve Kearney and Wayne Bennett, they put together a game plan that we knew would work.
"The game is about pressure over here. You put pressure on and the first one to break loses. We didn't break. They came up with some mistakes they don't really make and we were lucky to make the most of it.
"When Benji (Marshall) scored in the corner off Billy Slater's mistake, their heads went down. We huddled up and said 'this is our chance, we've got to take it'.
"The boys didn't want to let that go because you don't get very many chances against the Aussies."
Just as in 2005, when British fans got behind New Zealand to cheer them to victory in the Tri-Nations final at Elland Road, the 5,000-strong Barmy Army took some solace from England's disappointing performances by roaring them to another famous win over the old enemy.
"I knew they would be behind us, especially the Wigan fans," said Leuluai. "They're the best. To see them come all this way and still turn up to the game in their Wigan jerseys - and all the other club jerseys - and support the Kiwis was massive.
"All the boys appreciate them for that."