Like father, like son!

Regan King is used to leaving defenders not knowing where to look, but Leinster could tonight be forgiven for thinking they were suffering double vision.

The former All Black centre returned to Scarlets last year to take on a mentoring role with the young Scarlets three-quarters.

Little did he imagine his role would also include parental duties with the emergence of his son, Jacob Cowley, through the Welsh club’s academy.

Last week the pair created Pro12 history as the first father and son to play alongside each other. Dad Regan, 35, even shifted across to 13 to make space for 18-year-old Jacob, a second-half replacement, in a family midfield partnership, against Newport Gwent Dragons.

King said: “I’m really proud of Jacob but it makes me feel a bit old. I thought I would have hung up my boots before I got this opportunity, but the conditioners at the Scarlets have looked after me really well and I’m glad to have had the opportunity.”

It is a fine and rare achievement in any sport. Last year Brazil football legend Rivaldo played alongside son Rivaldinho for Sao Paulo club Mogi Mirim.

In 2012, former West Indies cricket captain Shivnarine Chanderpaul struck a 256-run partnership with son Tagenarine on a 40 overs match for Ghandi Youth Organisation. However it is a different story amid the physical demands of rugby.

Wales boasts its rugby dynasties. Only last month, Ross Moriarty followed his father Paul and uncle Richard to play for Wales at a World Cup.

While the Scarlets still glory in the influence of the Quinnell family over the generations. None, however, played in the same team at the same time.

Cowley, who grew up with his mother in Australia and then New Zealand, before joining his father in Wales last year, said: “I’ve watched my dad play but hadn’t had the chance to be with him.

"It was the first time we’ve been on the pitch together so wasn’t sure what to call him, so I called him by his nickname Reggie, rather than ‘dad’.

“But it was great to be out there with the old man. It’s been good to get to know him a bit more and really good to see how good he is at his job. Some people say it’s weird how we play the same and hopefully I can learn from him.”

The pair are now working under the guidance of ex-Wales fly-half Stephen Jones at Parc Y Scarlets. Jones returned to the Scarlets as backs coach, having cut his teeth in coaching at Wasps.

It came as little surprise that Jones should slot back into life in west Wales so seamlessly given he spent 14 years during two spells at Llanelli as a player.

However his impact on the exciting rugby being played by the Scarlets has been more impressive and reflected in their unbeaten start.

King said: “I have got a great respect for the guy, Stephen is one of the greatest players at this club, or in Wales. He seems to have gone away to Wasps and grown as a person and come back with a real purpose.

“The preparation we go through with him is very, very thorough. He has got high standards and if any move or drill is not done to those standards we have to do it again.

“That is what we need. If we are going to get things right on the pitch we are going to have to train how we play. He has brought a different mentality to the group. Everyone respects him so we buy in to what he says because he has been there and done it.”

Six wins from six have the Scarlets faithful excited, starved of success since winning the Celtic League title back in 2004. However they face their stiffest test of their credentials against Leinster at the RDS tonight.

Head coach Wayne Pivac said: “It will be the biggest test of the season so far. We’ve already won twice away this season but this will be a massive challenge against a Leinster team with their World Cup players back. ”