ROBBIE Tarrant did not have to look far for a mentor when he prepared to switch from North Melbourne's forward line to defence this season.
 
Tarrant's elder brother Chris spent the first 11 seasons of his 268-game career as a key forward with Collingwood and Fremantle, before transforming himself into one of the AFL's best key defenders.
 
Tarrant told AFL.com.au that ever since North coach Brad Scott asked him at the end of last season to consider moving to the backline Chris had been an invaluable sounding board.
 
"He's someone who made the transition really well himself, so he's definitely been someone that I've bounced some things off," Tarrant said.
 
"He's someone I speak to most weeks about upcoming opponents and how to play certain players.
 
"He's been fantastic and definitely a tool that I've utilised."
 
Tarrant got his AFL start in defence, playing nine games there from 2010-11, but it was as a key forward that the former Bendigo Pioneer established himself in the Roos' team over the next two seasons.
 
Tarrant's 2014 season was ruined by a tibia stress injury that had also sidelined him for nine straight games the previous season.
 
After managing just two games last season – one in the VFL and one in the AFL – Tarrant was forced to watch as Ben Brown emerged in his first season to cement a spot in attack alongside fellow tall forwards Drew Petrie and Aaron Black.
 
The Roos' decision to recruit former Carlton spearhead Jarrad Waite in last October's free agency period meant the squeeze for positions in North's forward 50 got even tighter.
 
Tarrant's move to defence was also sparked by the way star power forwards Tom Hawkins and Lance Franklin dominated the Roos' undersized backline in last year's finals series.
 
Scott Thompson, 193cm, Nathan Grima, 192cm, and Michael Firrito, 189cm, regularly conceded height and weight to opponents last season and for the most part held their own.
 
But as two-time North premiership coach Denis Pagan once said, you need gorillas to play on gorillas. And the Roos identified Tarrant, 196cm and 97kg, and Joel Tippett, 196cm and 94kg, as players who fitted that bill.
 
The Roos went with Tippett in the opening two rounds of the season after the former Gold Coast rookie's impressive pre-season.
 
Asked whether this made him worry about his standing in North's backline pecking order, the 26-year-old said he probably needed to start 2015 in the VFL to "get more confidence defensively".
 
Once Tarrant got his senior chance in round three against Port Adelaide he was certainly ready to go.
 
Manning Justin Westhoff for most of the night, Tarrant held the Port spearhead goalless while racking up 21 possessions himself, even drifting forward to kick a goal in the third quarter.
 
Tarrant's assignments did not get any easier over the next two rounds as he took on two of the best power forwards in the competition, Hawkins and Jarryd Roughead.
 
But North's emerging 'gorilla' stood up, restricting Hawkins to 1.2 in North's 16-point win and Roughead to 3.2 as the Hawks pumped the ball inside their forward 50 60 times in their 10-goal victory.
 
And last week at Blundstone Arena Tarrant kept Tigers duo Ben Griffiths, who was substituted out of the game with concussion after the first term, and David Astbury goalless.
 
But defence has not been Tarrant's sole focus this season.
 
Conscious that he also had to "help out offensively" the former forward has averaged 19.7 possessions a game (ranked seventh at North) this year and is third at the club for average rebound 50s (3.7 a game).
 
Tarrant is also fourth at the Roos for average contested possessions (8.2 a game) and eighth for average marks (5.2), while his strong defensive work ethic is reflected in his equal third ranking for one-percenters (2.7 a game).
 
It's been an impressive start to the season, but Tarrant says switching back into defence has been a "fair adjustment".
 
"The lucky thing was that I was able to train a whole pre-season as a defender and hopefully that holds me in really good stead for the rest of the year," Tarrant said.
 
"I know I've still got a lot of work to do but I'm slowly getting there."
 
Tarrant has played just 43 games since North took him with pick No.15 in the 2007 draft.
 
Shoulder injuries ruined his first two seasons at North before the recurring tibia injury sidelined him for all bar 15 games in 2013-14.
 
Tarrant admits he doubted whether his body would ever allow him to reach his potential when a tibia stress fracture was detected after North's loss to Adelaide in round 13 last year, but says post-season surgery has his body feeling the best it has in a long time.
 
"I probably didn't go as far as to think that I would retire, but you definitely have doubts," Tarrant says.
 
"We took two or three weeks to try and figure out what was going to be best for me and we came up with a surgery that so far has worked really, really well and so far I haven't a session since I've come back.
 
"I'm happy to be playing and contributing to the side and being fit enough to pull up well and train during the week is pretty important too."
 
Tarrant finds it hard to believe he is in his eighth season at Arden Street, a stint that qualifies him for free agency at the end of this season.
 
But the key defender played a straight bat when asked about his contract status.
 
"I'm just really enjoying my footy at the moment. I'm sure my manager and the club will speak at some stage and get something done," he said.