He hopes his first battle with the Kiwis as a coach will lead to something altogether more satisfying; a crucial step closer towards ending England’s long wait for World Cup success.
It was in November, 2005 when the scrum-half, who weeks earlier helped Bradford Bulls defeat Leeds Rhinos in an epic Grand Final, suffered that horrific injury.
Deacon had been reprising his club dominance with country, causing New Zealand all sorts of problems with what was widely regarded as his most positive international performance.
But then, with Great Britain 12-0 up after 23 minutes and Deacon having scored a first international try on his 11th Test appearance, a swinging arm from Nigel Vagana left him grounded and bloodied.
At first, it looked just like a nasty facial wound – not uncommon in the sport – but once he had been relayed back to the dressing rooms, it became clear the problem was far more severe.
Deacon had actually fractured the upper palate in his mouth and burst so many blood vessels there was a fear he could choke unless it was quickly stemmed.
Great Britain’s doctor, Chris Brooks, worked on him for two hours in the bowels of Huddersfield’s Galpharm Stadium and likened his injuries to those of a car-crash victim; the player required extensive surgery to his cheekbone, eye and palate with several metal pins inserted in his mouth.
Deacon was soon back in training but recalled to the Yorkshire Post: “That turned out to be my last international game.
“It was ironic. Everyone said I was playing my best game yet – and I had to go get carted off. It was good and bad in both senses.
“But it was a freak injury; I’d never heard of it before that or since. It still gets brought up in conversations sometimes because of just how freaky it was.
“It’s always tough against New Zealand. I was lucky enough to play in that Tri-Nations series against them and also when they toured in 2002 and, though we drew the series, we won the Baskerville Shield.
“This Kiwis side now are beatable. We know they are. They are not on a pedestal. We just need to put them under that pressure that they’ve not had yet and, hopefully, make them crack.”
Deacon is, of course, talking about tomorrow’s World Cup semi-final at Wembley when, as Steve McNamara’s assistant, he hopes to be able to plot the downfall of a New Zealand side that has swept past all before them so far.
His progression to the role has been swift; he only retired two years ago following an Indian summer at Wigan Warriors where he then joined the coaching staff.
But, in only his second season, Deacon has helped head coach Shaun Wane deliver a Super League and Challenge Cup double and, when former Bradford team-mate James Lowes stood down as England No 2 to take over at Leeds Carnegie in June, McNamara approached him about stepping up at international level, too.
An intelligent and thoughtful player, it is no surprise the 34-year-old has taken to coaching with such alacrity.
McNamara has long respected his knowledge, having replaced Iestyn Harris with Deacon as Bradford captain in 2007.
“I’d been involved the last 18 months with England on game day, running messages, and obviously had two years’ experience at Wigan, which has been a great grounding for me,” he said.
“I was surprised he came to me and said he wanted me to be an assistant, but really excited, too.
“I was confident in my own ability that I could do a job and I’m hoping I’ve proved that.”
England have, though, yet to really find their rhythm in the competition, illustrated by a patchy 34-6 quarter-final win over France.
There will be no room for any error tomorrow and Deacon added: “We’re well aware of what we’re up against. New Zealand have had a tremendous tournament, nearly faultless really.
“Samoa tested them for a short period in their first game – put them under a bit of pressure – but they came through that.
“We know we have to be at our best. A lot has been said about our performance against France. That wasn’t us really.
“We know we’re better than that. We need to be and that’s what we’re planning.”
Plenty of questions have been asked about the efficiency of the current England half-back partnership of Kevin Sinfield and Rangi Chase.
“I know that half-backs get a load of stick but – and I know more than most – if the team around you aren’t on their game it’s very, very hard for a half-back to produce,” offered Deacon.
“When the players around you are doing their job then your job becomes 10 times easier and it makes you look good when, really, you’re probably doing the same things you usually would.
“That’s why it’s a team sport; everybody has to play well, especially against New Zealand.”
Deacon is proof of that; when he left Odsal at the end of 2009 after more than 300 games, countless trophies and approaching his 31st birthday, many thought he was on his way out and would be a bit-part player at Wigan.
Yet he proved integral as they stormed to the Super League title in his first season.
“I didn’t become a better player by going to Wigan,” explained Deacon.
“I still had the same attributes. If anything, I was probably just getting a little bit worse season by season just with age.
“But I had great players around me, a good coaching set-up, good systems in place and everyone knew their job.
“When everyone knows their role and all are doing it well it makes everyone look better.”
Hopefully, all those boxes will be ticked tomorrow and England will be looking good again.