SYDNEY Swans defender Heath Grundy has taken until his sixth season to finally crack the 50-game milestone but it's been more than worth the wait.

Grundy has emerged as a key member of the Swans' backline in 2010, having already matched wits with Nick Riewoldt twice and featured among his side's best in each of their three games to date.

And the secret? Confidence, according to both the player and his coach.

The 23-year-old was so lacking in belief at times that he struggled to convince himself that he had the ability to play well at senior level.

"At times, you lack confidence and there were probably a few times where it crossed my mind," Grundy said on Thursday as he prepared for his 50th game on Saturday against North Melbourne.

"But in the last few years, going down back has helped me a lot. I've got a lot of confidence out of that and I feel a lot more comfortable down there.

"I played a little bit more down back, actually, as a junior than I did as a forward so I always knew I could play down there. It was just a matter of getting a chance."

Swans coach Paul Roos also conceded there were times when he wondered whether the 192cm key position player with sure hands could make the grade.

"We knew he had good talent but ... we found it hard to find a spot for him. He struggled a bit with Hally and Mick [up forward]," Roos said.

"He worried a bit too much about where they were going to lead and what they were going to do. He tended to sit back and watch a bit at centre half-forward.

"Most of the time we did play him down back, he played really well but we had Lewis Roberts-Thomson, Craig Bolton, Teddy Richards, so he struggled to get in."

Roos said the support of Grundy's teammates, including mentor Craig Bolton, was crucial in changing his mindset.

"His teammates in the middle of last year were really telling him that they wanted him in the team and that they believed in him," he said.

"He probably didn't believe in himself enough the past two or three years but once he got that belief... you see him go out and he looks really confident when he plays."

Leo Barry's prolonged absence in 2009 gave Grundy his chance down back and he made the most of it with several assured performances.

A summer spent chasing Adam Goodes around the Swans' Lakeside Oval training venue further developed his skills and his self esteem.

"You're not going to get a better runner and a footballer than Goodesy. It was good to beat him in a few marking contests," Grundy said.

"If you can get a couple of grabs on him and stop him from getting the ball, you can try and beat anyone."