Cameron Munster is standing on a soggy short side behind Parramatta's ruck at Bankwest Stadium.
Clint Gutherson is opposite, and quickly turns Sydney's best stadium into a cattle stockyard.
A blue and gold kelpie with a dodgy ponytail and mongrel mood to match.
As Munster swings to the open side Gutherson does the same, skirting west along the stockyard fence for 30 metres before the ball lands with Josh Addo-Carr.
Gutherson is on him. The fastest man in the game puts boot to ball because the Eels No.1 is nipping and nagging away.
Munster has followed the play and can smell points when he picks up the Steeden, five metres out from the line.
Gutherson sniffs it too. He'll run 9.35 kilometres up and down the sodden turf in total, chasing everything bar Melbourne's team bus en route to a telling Parramatta win.
Breaking down Gutherson's try-saver on Munster
As Munster reaches out to plant the ball, Gutherson is slipping, sliding and smacking the four points away.
It's the 36th minute, the fourth try snuffed out and the kelpie is in command.
"That last-ditch effort, if he doesn't put in that second effort, he doesn't give himself a chance to stop that try," says Billy Slater, the original sheepdog that changed everything for fullbacks.
"Munster scores that, Melbourne probably win the game.
"Those efforts, they're not just important, they are the difference. And fullbacks think of themselves these days as the difference. 'I've got to be the difference'.
"Whether it's defensively or with the football in hand. The mentality of the position has certainly changed."
Gutherson puts on first-half defensive masterclass against Storm
Class in session: the unofficial fullback textbook
For all the focus on a fullback's ball-playing, the No.1 now carries a laundry list of duties without it in the modern game.
"Don't get me wrong, Gutho is our number one. But any sort of discussion around recruitment and fullbacks for the back-ups in our squad, that's the first thing I want," Eels coach Brad Arthur says.
"It's the one thing I talk to our [recruitment staff] about, their defence.
"Your fullback has to get in short sides, get up into the line on a long shift, plug holes, get the numbers right on the run, talk to their tired forwards, physically get in there on their try line, and then worry about defending the kick.
"When Gutho first started doing it, and he'd be the first to admit it, he was horrible at it.
"It just took a lot of work and he's never been shy of that has he?"
What makes a good defensive fullback
Plenty have played their part in adding to the defensive load at the back over the years, with Garry Jack and Gary Belcher the two fullback forebears of the 1980s.
"I'm not sure it's changed that much," Belcher says.
"The best fullbacks have always talked and communicated to keep their defensive lines in order. That was the expectation I put on myself."
And after a one-on-one with Tim Sheens, the coaching father of so many nuances in the modern games, the expectation grew further.
"Sheensy and I had a conversation, probably around 1990, where I said I could jump in the middle of the line if we're defending our line," Belcher says.
"You can't do much from behind the tryline and that's how we worked it. As long as I could still get out wide and cover defend Sheensy could see it working and that's how we did it."
From Belcher and Jack came Anthony Minichiello, the bastion of Ricky Stuart's brutal Roosters defensive regime in the early 2000.
And then Slater.
His famed 2003 debut against the Sharks with No.3 on his back – where Cronulla led 22-0 until Slater went to dummy-half, shimmied, shimmed and whooshed with 60 metres of pure pace – was Craig Bellamy's first as an NRL head coach.
And Slater's first at fullback. Ever.
"When you come into first grade and start playing a position, there's an unofficial textbook of how you play that position," he tells NRL.com.
"That's been created by the players previous to you.
"When I first started playing fullback, the great fullbacks were Darren Lockyer and Anthony Minichiello – who had just won the Golden Boot – and those two were extremely different types of fullbacks.
"I tried to blend their strengths in with my strengths.
"Without the football, if you understand the game, and are willing to work hard you can put yourself in the positions to help your defence.
"Things like cues to get into the line. The first one is when your team's under pressure and they've created a quick play the ball.
"The other cue is when there's three key position [opposition] players on the one side.
"So if you've got your seven, six and one all on the one side of the field, you need to either push a defender over to create another number or you need to jump in there yourself."
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Video made the Storm star
Fullbacks run further, faster and for longer than anyone else on the paddock.
More than anyone else, Slater added between the ears on top of the miles in his legs.
Winning started Monday for the Storm No.1. Not in the front office, but a few doors further down at Melbourne HQ, where he and predecessor Robbie Ross would pore over video footage of the opposition.
"We were still on the VCR, but there was a fair bit of tape looked at, conversations at training," Slater says.
"He sat down with me a lot in that first year and really accelerated my knowledge by just giving up his time."
Fifteen years later, not only did all that video have Slater being pencilled in as a future Immortal, it helped save him being rubbed out of one last game.
I think Roger Tuivasa-Sheck is probably the best try-saving fullback going aroundBilly Slater
When Slater faced being suspended out of the 2018 grand final, his last outing before retirement, those countless hours of video analysis became part of his successful defence of a shoulder charge on Sosaia Feki.
Slater told the judiciary panel that prior to Melbourne's preliminary final win over Cronulla, he had watched every single try scored by Feki and Edrick Lee that season as part of his meticulous, weekly preparation.
As a result he anticipated Feki's path to the line, albeit with his own shoulder in an awkward position as he tried for a ball and all hit.
"Towards the end of my career I was watching opposition wingers and which arm they liked to carry the ball in to score a try," Slater says.
"So if it's a right side player and he liked carrying the ball in his left hand to score a try, I would have that knowledge going into that corner post. Then knowing whether they liked to step back inside or go for the corner.
"That little bit of knowledge, it's all instincts once you're out there because it happens so fast.
"But understanding that knowledge and what they like to do, certainly puts you in a better position that not knowing it."
Again, Belcher can see the precursors from his career 30 years ago.
It was Jack Gibson that first brought video analysis to the game from his visits to NFL franchises, with Canberra going beyond the usual "one copy of the game, shot from one angle" as their dynasty took off.
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"There wasn't as much structure in our game back then, so how much video would've helped us I'm not sure," Belcher says.
"I'd say that's the big difference now. Again I know Sheensy and the Raiders were one of the first teams to make it a focus.
"Otherwise we had simulated training drills – the three on four, three on two – that's how we would recreate [defensive] scenarios.
"But you know I also came through in the old tackle bag days, they weren't that hard to bring down so I'd say the guys now have a fair bit more to work with."
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Tackling in the land of giants
The information and preparation piled into players is unrecognisable compared to their '80s and '90s predecessors.
So too the players themselves. Most fullbacks these days can match the back-rowers of yesteryear on the scales.
Those big men now regularly clock in at over 110 kilos.
Twice against Melbourne last week, Gutherson slid his 95-kilo frame beneath the wheels of Tui Kamikamica (110kg) and Nelson Asofa-Solomona (115kg) with trysaving efforts.
"Absorbing the contact is something that I used to train for and I'm sure a lot of the fullbacks train for now," Slater says.
"When you're on the try line coming up against someone 30 or 40 kilos heavier than you and they're trying to get to the ground, well, sometimes it's best to sometimes let them get to the ground and just keep your body in between the ball and the grass.
"That sometimes surprises those big guys that want to try and bump you off and they want that collision.
"I think Roger Tuivasa-Sheck is probably the best try-saving fullback going around.
"You can see the pride in Roger when he puts himself into those tackles. He bounces up and he's really proud of his efforts and what he's done for his team.
"He seems to love getting into the right position to save a try and he's really perfected the art of that, whether it be absorbing the contact or getting the body into a certain position that puts him underneath the ball."
Brad Arthur offers another perspective. Safety in numbers.
"You do bits and pieces of that in wrestling and training," Arthur says.
"But what Gutho does so well, if he can get the line and his numbers organised, then it's not a mismatch because he's not doing it on his own.
Gutherson and Mahoney combine to stop big Nelson
"You look at those tackles, he's got our smallest player on the field Reed Mahoney involved in a couple of those too.
"To make those tackles on the big blokes, it can be too hard to do it on your own. So get your teammates involved, and Gutho's good at organising his line so that happens.
"You can't do much on your own in our game anymore, it's too hard."
The flow-on effect
Back to the Bankwest stockyards.
After Gutherson gets his hand in the way to deny Munster, the ball bobbles its way to Kenny Bromwich.
From the very next play, the Storm swing to the open side and Reimis Smith scores anyway.
Parramatta and Melbourne trudge up the race with scores level. Just as they did in the first week of last year's finals.
Match Highlights: Eels v Storm
In 2017's version of NRL groundhog day, the Eels held a surprise 10-4 lead before succumbing to the eventual premiers.
In 2021 they hold on. Maika Sivo's take-off and touchdown with George Jennings's ball steals the show and two points.
But as Slater started us off, the fullback is "the difference".
Four tries saved in a four-point game – easy to count those numbers.
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"Actions are infectious," Slater concludes.
"Whether they're good or bad. If you have poor actions and lazy actions in your defensive team, that's going to be infectious, that's what's going to be acceptable within the group.
"But if you have good actions, desperate actions, never give up actions and that's celebrated internally, that is what's going to infectious throughout your team."
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