Rugby World Cup 2019: All Blacks' Luke Jacobson on ' top of the moon' after World Cup call-up

All Blacks newcomer Luke Jacobson admits to some anxious moments leading up to the instant he heard NZ Rugby Chairman Brent Impey announce his name as one of the 31 players to defend the Rugby World Cup next month.

The Chiefs' powerhouse was named to the New Zealand Rugby Championship squad in early July, but was only able to make a brief impression as a concussion issue suffered at training limited his impact to a test against Argentina in Buenos Aires.

The 22-year-old shone in an appearance for Waikato in their Mitre 10 Cup fixture against Counties on Saturday, and he was quietly confident he'd proven enough to make the cut for Japan.

"I was really nervous this morning and last night," said Jacobson. "Any little buzz on my phone I was pretty scared of looking at.

"I truly didn't know. I was pretty happy with the work that I had been able to put in leading up to it. I felt I did my best, so I was happy with that."

In the end, Jacobson was home alone in front of the TV when he discovered his World Cup fate.

"I shot back hoping some of the flatmates would be home," he laughed. "It was pretty similar to being named the first time - just a rush of joy, really exciting and im on top of the moon.

"There were a few more fist pumps going around."

Rugby World Cup 2019: All Blacks' Luke Jacobson on ' top of the moon' after World Cup call-up

The versatile loose forward was a revelation for the Chiefs through their Super Rugby campaign, injecting a welcome dose of confrontational and combative play, combined with slick ball skills and a relentless motor.

He beat out the likes of Jackson Hemopo, Vaea Fifita, and Liam Squire - who's on stand by as an injury replacement after declaring his availability late - for the specialist blindside flanker berth. 

Coach Steve Hansen is unfazed by Jacobson's unproven test record and offered some glowing remarks that suggest he has grand designs for the young flanker.

"It doesn't matter if you've had one or none or 100 [tests]," said Hansen. "If you're good enough, you should be available for selection.

"He's a former [NZ] U-20 captain so he's got good leadership skills. Defensively, he's one of the best hitters in the game. He's a good ball carrier and he's just a smart rugby player. We think he's got a big future."

Jacobson insists he's completely over the concussion problems that put paid to his Rugby Championship campaign and is ready to make soak up as much knowledge as he can in the All Blacks environment over the approaching months.

"I'm going to be learning heaps at training… I'll be in there training with the best. Just looking forward to it.

"Any little chance I get I'll be going 100 percent at it."