North director of coaching Darren Crocker has been there since the very beginning of Brent Harvey's AFL journey, watching his evolution as a footballer and as a person.

The 49-year-old is, in fact, one of the very few people who can say they have had the luxury of playing alongside Harvey and then coaching him.

Crocker, a 1996 premiership player who appeared in 165 games for the Roos between 1985 and 1998, played 12 matches with a fresh-faced Harvey in the twilight of his career.

He then went on to coaching Harvey in his role as a Roos assistant from 2004, which included stints as caretaker coach in 2009 and fill-in coach when back surgery sidelined Brad Scott last year.

Crocker said he had vivid recollections of a young Harvey entering the AFL system after being drafted at pick No.47 in the 1995 national draft.

"When he first came in, he looked like a 16-year-old, not an 18-year-old that had gone through the draft," Crocker told NMFC.com.au ahead of Harvey's record-breaking 427th match.

"He had such a young face, he was so small, but he always came in with that pace, he came with that step and he just needed to become comfortable in the environment.

"I remember him playing one game at the end of '96, and being the determined bugger that he is, that was never going to be enough for him and he's then worked really hard to make sure he got lots more of that."

Their bond began in an off-season team trip soon after Harvey joined Arden Street, well before his official debut against Richmond in round 22, 1996.

Crocker recalled the moment he reassured Harvey's father, Neil, that he would take the wide-eyed teenager under his wing.

"I'll never forget putting my arm around his old man at the airport when he was coming away on his first footy trip and telling him I'd look after him," Crocker said with a laugh.

"His old man said, 'Don't look after him too much, he's got to learn to fend for himself' – his old man is pretty hardcore.

"To see that kid grow into the person that he's become, the player he's now been for such a long time, I just feel a real honour and privilege to have been involved with that."

Harvey quickly earned the respect of his fellow teammates with his professional approach, largely thanks to what Crocker described as a "never give in" attitude that remains quite evident even after 21 years at the elite level.

He added the key to their long-lasting friendship was transparent conversations, and that Harvey deserved all the praise for what he had achieved over his distinguished career.

"I don't know whether it's because the player-player relationship and then the coach-player relationship that I've felt that I've always been able to have an open and honest relationship with 'Boomer' and let him know where I felt he needed to continue to improve and work on with his game for the sake of the team," Crocker said.

"I don't think there's many people that can take credit for Boomer's career other than Boomer himself with how hard he's worked, how dedicated he's been and disciplined to get the best out of himself."

The coaching director said the Roos were determined to make Harvey's historic achievement even more memorable by securing the win over an in-form St Kilda outfit on Saturday night.

"It's an enormous milestone for the club," Crocker said.

"I've been privileged to have been involved with him for so long.

"With any milestone, the most important thing is that you don't get caught up in the milestone itself, you actually still execute what you need to execute to win the game, and when you win the game they're the most memorable milestones."