The Welsh flyer challenging Addo-Carr as Nines' fastest man

His sister has found fame as a reality TV star in the UK, and this weekend Regan Grace is set to steal the World Cup 9s show as he challenges Josh Addo-Carr's title of rugby league's fastest man.

"If he gets in the clear, put down your beer and watch," is the tip from Wales' jovial coaching staff when asked about the St Helens winger.

Blink and you might miss him though.

Grace was clocked at a rapid 36.7 km/hr "with ball in-hand" during a game against Hull KR, speed which only Addo-Carr has trumped over the past two years in the NRL.

The 22-year-old Welshman weighs in at just 79 kilos but packs serious offensive punch with 22 tries in 33 games this year, the last of which was St Helens' Super League title win over Salford.

His sister Lateysha Grace featured first in British productions of Big Brother and The Valleys before landing her own MTV series Million Dollar Baby last year.

Regan's rise has been similarly meteoric.

He only found his way to rugby league late in his teens after pursuing a career in union alongside the likes of junior teammate Owen Watkin, who is now lining up at outside centre for Wales at the World Cup.

"Rugby league's still quite small in Wales, it's definitely still got some growing to do, but I remember seeing a leaflet or pamphlet for a local side and I picked it up basically to keep fit for rugby," Grace told NRL.com of his formative years.

"I was playing amateur rugby in Wales and someone told me when I was around 17 I should have a crack at some of the trials.

"I had nothing to lose, why not, and I had a run with St Helens.

"I signed one year, and then another year and next thing I know I've been there five years and we've got a grand final win."

Hailing from the seaside town of Port Talbot on Wales' south coast, population 35,000, Grace battled homesickness and considered calling it quits during that first pre-season at St Helens.

"I couldn't lift my arms after that first gym session," he laughed on Tuesday.

"When I first joined rugby league I was obsessed with putting on weight.

"I just couldn't though, it's just not me. I couldn't sacrifice my speed for size though.

"I'd be up smashing these protein shakes with the caffeine in them, not realising how much there was so I'd be awake all night unable to sleep.

If he gets in the clear, put down your beer and watch

Wales coaching staff on Regan Grace

"Took me a while to work that out as a tiny little 17, 18-year-old. I would look at all the other Academy boys and think 'I need some size here' but we worked it out in the end and I'm glad I stuck with it."

Rugby league and the World Cup 9s benefits too from that decision to tough it out.

Grace is contracted with St Helens until the end of 2021, but is keen to give the NRL a crack later in his career, making note of Justin Holbrook's move from Saints to take charge at the Titans next year.

In the meantime, he is sizing up the open spaces on offer at Bankwest Stadium, having made a typically rapid journey across the globe to be here.

 "Hopefully I get to use my speed, it's an exciting concept," Grace said.

"I think our whole team is suited to that style - we're a bit of a smaller, quicker team I'd say so hopefully that works to our advantage.

"I flew out for Oz at 8pm on Sunday England time, and I touched down Tuesday morning here in Sydney.

"Basically lost two days and didn't get to celebrate the grand final too much because I had to be on the plane and out here.

"But of course you want to be representing your country. It's an easy choice."

For ticket and travel packages for the Downer Rugby League World Cup 9s Sydney 2019, head to nrl.com/tickets.