There has barely been a clash like it since Shane Williams faced up to Aurelien Rougerie back in the day, with the 6ft 4in Frenchman bouncing the little Welshman backwards as a dodgem car might treat a Dinky model.
That was in the first half, mind, of their clash in Paris in 2005.
In the second 40, Williams ran so many rings around the man who had given him such a rough ride earlier that Rougerie must have felt dizzy.
Anyway, let’s press the fast-forward button.
Last weekend, Kieran Williams opposed Stuart McCloskey in the Ospreys v Ulster encounter at the Liberty Stadium.
If it were boxing, the match-up would never have been allowed.
There stood McCloskey, big even by the standards of modern midfield men.
Indeed, were he around in the 1970s, the 6ft 4in, 17st 7lb Ulsterman would have looked down on many second rows.
Opposing him last Saturday was a veritable Lilliputian by today's standards.
How would the 5ft 10, 12st 6lb Williams cope against the Gulliver opposite him?
Not too badly at all, as it happens.
McCloskey did set up a try early on with quick feet and clever offloading but his fellow No. 12 wasn’t on the scene when the damage was done. And the Ireland centre did cross for a touchdown of his own in the final quarter after collecting a precise cross-kick from team-mate Bill Johnston.
But, again, 22-year-old Williams’ dabs weren’t on that one.
It actually turned into a memorable afternoon for him.
One line-bust from deep saw the player Dan Lydiate has dubbed the Ospreys’ 'little cannonball' hurtle upfield with the Ulster cover splintered. The defence eventually regrouped, but only after the Ysgol Gyfun Ystalyfera product had made 40 metres.
There were also selfless carries into the heart of the cover, with the youngster acting as a target for his pack and giving the home team priceless go-forward.
And 11 successful tackles out of 12 attempts pointed to a solid defensive shift.
Social media lit up in appreciation of the Neath-born player’s effort, with one contributor reviving previous comparisons of Williams with a Welsh rugby legend, describing him as “a reincarnation of Scott Gibbs when he first burst on the scene with Neath. Low centre of gravity, deceptive in strength and speed off the mark”.
Let’s just wait and see.
Gibbs was also fearless and had iron-hard mental strength. Anyone calling him a complete one-off would be close to the mark. He had an uncanny ability to spot weak shoulders and blasted throughout countless opposition defences. There are warriors and then there was Scott Gibbs.
That said, he was roughly the same dimensions as Williams when he made his Wales bow in 1991, tipping the scales at 12st 7lb, so it’s perhaps understandable why he’s mentioned in discussions about the new boy close on 30 years on.
Whatever, the Osprey’s effort against Ulster delighted his attack coach. “He had a really good game against a very experienced PRO14 player in McCloskey,” said Matt Sherratt.
“Kieran showed what he does at Welsh Premiership level.
“He carried the ball really well and gave us front foot; he put a nice kick in.
“He’s someone who’s really stuck his hand up.”
Injuries have prevented Williams breaking through earlier.
After a terrific campaign for Wales U20s in 2017, during which he achieved multiple turnovers and miles and miles with ball in hand, he was expected to step up seamlessly into senior rugby, notwithstanding his relatively small frame.
But a series of bumps hampered him, including an ankle problem that cost him five months on the sidelines.
Inactivity is the exact opposite of what a young player needs and while he was in plaster and bandages, others were banking experience and forging ahead.
The Ospreys at no stage gave up on him, though, and awarded him a first professional contract last year.
Ex-Wales skipper Gareth Llewellyn, who coached Williams at Neath, told WalesOnline after that deal had been pushed through: “He’s a promising young player.
“One of his strengths is his strength.
“He isn’t a huge guy but he’s a pocket-battleship who makes yards on the gain-line.
“Some people have likened him to Scott Gibbs and he does have quick feet and fast hands.
“At Premiership level he’s fantastic.
“We won’t really know how good he is until he has had a run of opportunities at regional level.
“But he’s ticked all the boxes in the Welsh Premiership.”
Now we are learning he is capable of doing it on the regional scene.
Maybe the magic men who are the conditioners at modern-day rugby clubs could yet bulk up Williams if that’s what is required. “He plays at No. 12 and inside centres are in the firing line,” said Llewellyn, who played 92 times for his country.
“So he’ll need to make sure he is up to the mark physically for professional rugby.
“You have to be able to compete physically. If you are not able to, you are in trouble.
“He will need to get himself in condition for the senior game.
“It is right to say Gibbsy wasn’t that big before he went to rugby league. But he came back a different animal and became renowned for his physicality.
“It isn’t an overnight job. It can take a couple of years to do.
“But there are conditioners and dieticians in the professional game who can perhaps accelerate the process.
“Kieran also needs to learn more about game-management, but that comes down to playing rugby. The more different situations he’s exposed to, the more rounded he’ll become as a player. That’s the same for every young player. It’s the way they learn.
“For me, he’s a very good prospect.”
It helps, too, that Williams is coachable.
Such things matter.
A former Wales international spoke highly of Dragons youngster Ben Carter the other day, calling him one of the most coachable players he had come across. “He just wants to learn and is willing to do anything to get better,” the ex-forward said of the lock.
The same applies to Williams.
He is also utterly grounded. “He’s a great kid who always wanted to play for Neath if he wasn’t involved with the Ospreys,” said Llewellyn.
“He’d give his all for the club and was liked by everyone.”
Rome wasn’t knocked up in 24 hours and Williams may still need to acquire some extra physical ballast.
But the signs are encouraging.
His partnership with Owen Watkin a week ago worked, with the pair functioning in attack and defence.
The more he plays, the more he will make his own distinctive mark.
It happened with Mike Phillips. When he started, people were comparing him with Terry Holmes, but Phillips was always more than a mere retread. Eventually, he became known for what he offered in his own right.
Expect that to happen to Williams.
And expect to hear a lot more of him in the coming seasons.
He’s a young player with much to offer.
