WELLINGTON –

Loose forward Shannon Frizell was surprised and delighted to be summoned to the All Blacks' Rugby World Cup squad on Friday, having been wearing a cow suit at a gym session only hours before the call from the team's staff.

The Tonga-born 25-year-old was overlooked on Steve Hansen's initial 31-man squad but flew off to Japan late on Friday to replace injured rookie Luke Jacobson, who was ruled out of the tournament by a delayed onset of concussion.

Capped five times for New Zealand, Frizell was at the gym earlier on Friday wearing a white cow suit to promote Tasman's match against North Harbour in the nation's provincial rugby competition.

The "Wear Ya Onesie Sunday" promotion urged fans to turn up in jump suits, or "onesies," to the weekend clash.

Frizell, instead, will be back in his All Blacks kit, pressing for a spot in the blockbuster opener against South Africa in Yokohama on Sept. 21.

The versatile Frizell can play lock, No. 8 and blindside flanker but his selection ahead of experienced No. 6 and Tasman teammate Liam Squire was a surprise for some New Zealand fans.

"I always hoped for a call like this, and I got it," a thrilled Frizell told reporters at Auckland Airport late on Friday.

"I was surprised by it ... I was getting ready for bed and got a message, so I called him straight away, the manager. I couldn't go to sleep until later.

"I called my mum straight away. I just said 'I'm going to Japan today' and she was just screaming."

He replaces highly rated 22-year-old Jacobson, who battled a concussion in 2018 and only returned to rugby in March after eight months out.

"I'm gutted for him, (but) he'll come back fitter and stronger. At the same time, I'm grateful for the opportunity," said Frizell, who missed the All Blacks' final World Cup warmup against Tonga and the previous two tests against Australia.

Overlooked Squire opted out of the Southern Hemisphere's Rugby Championship after an injury-blighted Super Rugby season but wrote on social media last month that he was "100% available" if injuries struck the All Blacks.

Hansen told reporters at the team's base in Kashiwa, Chiba Prefecture, that it was still too early for Squire to be considered.

"It's happened right at the beginning of the tournament," he said of Jacobson's injury.

"So nothing has changed from that point of view for him."