ALL WEEK debate raged whether Nat Fyfe works hard enough without the ball. 

But you can bet your life Fremantle coach Ross Lyon's No.1 concern won't be how to replace his superstar's defensive efforts if he is ruled unfit for the Western Derby.

It was a throwback to a different era watching the midfield beast being helped from the ground in the arms of two trainers, his feet dragging like a punch-drunk boxer, during Sunday's nail-biting win over St Kilda.

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Attacking the footy in fearless style like he does dozens of times per game, Fyfe came off second-best from a head clash with young Saints defender Josh Battle.

The Dockers were 10 points up and just doing enough to hold St Kilda at bay when Fyfe went down at the 15-minute mark of the third term.

As Lyon noted post-match, from there the contest could have gone either way.

"It was really important we displayed great character and competed fiercely for our captain, and I thought we did that," Lyon said.

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"There were some mistakes, but I thought we really hooked in, showed great grit and got the four points, so it was really pleasing."

Losing Fyfe sent alarm bells ringing and, if Brandon Matera had not produced an inspired three-goal second half, the five-point win could easily have been a troubling home defeat.

It didn't need a game-ending concussion to remind us, but when teams – especially developing outfits like the Dockers – lose one of the most dominant players in the game, we remember exactly why they are so valuable.

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What they can do better than 99 per cent of the competition, not the little things others can cover for them.

There was always going to be attention on Fyfe's defensive workrate at Optus Stadium after he was criticised by two highly respected premiership coaches.

Mick Malthouse and Paul Roos might have a point about his two-way running, but there are clearly rules for some and rules for others in the AFL.

When you are at the absolute pinnacle of the game and ranked by many as the No.1 player in the sport, you have more freedom to push forward, create and help your team win games, not avoid losing them.

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Richmond has a system that gives Dustin Martin a licence to attack at will, and so does Fremantle for Fyfe – a fact he acknowledged after claiming his Brownlow in 2015.

"Our midfield is such a complementary midfield," Fyfe said in his acceptance speech.

"All AFL clubs would understand that there are guys that play roles behind the scenes.

"Nick Suban, Tendai Mzungu, Matt de Boer, guys like that who allow me to hunt the footy and get the pats on the back while they're seeing out my man on transition, basically."

That's why, when the ball escaped from stoppages against St Kilda, Fyfe paid scant regard to tagger Jack Steele – but that doesn't mean he didn't defend.

The skipper roamed the ground, pushing from stoppage to stoppage, sometimes floating forward to exploit his marking prowess and others pushing back to find a spot in the Dockers' defensive zone.

When the Saints clicked up a gear in a four-goal second term, Fyfe became more desperate, getting a hand in here or there, and laying three of his six tackles.

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Up to his collision, Fyfe had worked through close-checking from Steele to pick up 23 disposals, lay six tackles and win six clearances - three directly from crucial centre bounces.

It wasn't the Brownlow medallist at his domineering best, but he was still a huge reason why Freo's nose was in front, helping surge the ball forward at every opportunity.

"Steele played him really tight. At half-time he had 15 (14 disposals) and lots of clearances (four), so I thought he was winning the battle," Lyon said.

"He kept his eye on the ball and he sets a great standard."

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Concussion symptoms are notoriously tricky to predict, but the brutal nature of the hit and the fact Fremantle only has a six-day break has thrown Fyfe's availability for Saturday night's clash with West Coast into serious doubt.

But one thing is for sure, if he can't get up to face the in-form reigning premiers, nobody will be talking about how much Fremantle will miss Nat Fyfe's two-way running.