The negating utility appears certain to be assigned a big job against the Tigers, whether it be on one of their three gun midfielders – Trent Cotchin, Dustin Martin or Brett Deledio – or perhaps a defensive playmaker like Bachar Houli or Chris Newman, whom he blanketed when the clubs met late last year.
When AFL.com.au spoke to Armfield, he hadn’t been informed about his specific role but was prepared for all contingencies. He was respectful of the Tigers' talents but believed the Blues would "get the job done".
Armfield has every reason to be confident in his ability nullify a superstar. Most recently he lassooed Adelaide's rampaging Patrick Dangerfield in a NAB Cup game at AAMI Stadium.
In three quarters, Armfield limited Dangerfield to 16 touches (just six kicks) and one goal, while having 13 touches and slotting two great goals himself.
He played down the effort, insisting the NAB Cup is the stage for experimentation.
"For all I know, Dangerfield was trialling a different strategy," he said.
Besides, Armfield adds, he's done better stopping jobs on the likes of Newman, Collingwood's Heath Shaw and former Port Adelaide runner Danyle Pearce.
But there were some eye-catching features of the Dangerfield job, most prominent being Armfield's you'd-have-to-see-it-to-believe-it feat to run down the speedster from behind – twice.
Few could recall anyone doing it even once. After all, Dangerfield has won the AFL Grand Final Sprint for the past two seasons – a fact his Armfield was acutely aware of.
Armfield virtually accepted that the pack-busting Crow would win his share of hardballs, so he concentrated largely on limiting his outside run. The no-nonsense Blue was well equipped for the task, being among the top three at Carlton for straight-line speed. (The others are the small Jeff Garlett and the tall Shaun Hampson.)
"I was lucky both times," Armfield said. "One time he took his eye off me and I got in closer than he expected, and the other time he fumbled.
"But you can’t get carried away with that, because it might be the third time that he gets away and kicks a goal."
It was a throwback to his younger days playing rugby union in his native Perth. (Remarkably, he didn't convert to "Aussie rules" until he was 17.)
"I've still got some of that rugby mindset – I just love chasing and tackling," he said. "But I've had to change my technique a bit so I don’t give away frees for in-the-back."
Armfield would love more roles in the midfield, where the action is, and has helped his cause by improving his endurance. But he knows his opportunities might be limited, given the Blues are well stocked with potential stoppers, from chief tagger Andrew Carrazzo to the likes of Ed Curnow, Aaron Joseph and the sidelined David Ellard.
Armfield has learnt a lot about tagging from his teammates, particularly Carrazzo, and also regular tag targets Chris Judd and Marc Murphy – both of whom have shared with him their likes and dislikes, and whom Armfield often opposes at training.
The 26-year-old remains "prepared for change – from game to game, and within games".
True to his status as Carlton's reigning best clubman, he is "happy to do whatever, wherever".
He enjoys the variety, the responsibility of playing on a gun and, consequently, the chance to shape the outcome of games.
"I'm not the most skillful player so I have to make the defensive side of my game a strength," he explained. "The chasing, tackling, pressure – things that go relatively unnoticed from outside but are noticed within the club. If you don’t do those things, you soon find out about it."
A late starter, Armfield hopes to be something of a late bloomer. At 26, he feels there is still great scope for improvement.
He says his rugby background has probably delayed the development of the required 360-degree awareness, game sense and kicking skills.
Armfield is becoming more confident in his kicking, where once he preferred to handball. (In the past two seasons he kicked 63 per cent of the time, compared to 44 per cent in his first three seasons.) He also wants to develop his left-foot kicking.
With the help of Blues forward coach John Barker, he now has a goalkicking routine. But it's not fail-proof.
"I tend to know in the warm-up if my goalkicking is on or not," he said.
Out of contract at season's end, Armfield hopes continued good form will stitch up another deal.
He has come a long way since the sleepless nights of his debut season of 2008. He recalls tagging North Melbourne champion Brent Harvey that year and conceding 30 disposals, three goals and three Brownlow Medal votes.
"It's all about process," he said. "If you know you've done everything possible to prepare, you can sleep a bit easier."
Dennis Armfield is a midfielder/forward in NAB AFL Fantasy. He averaged 62.9 points in 2012. Register your team at our AFL Fantasy Hub
