WITH a dearth of key defenders in the AFL, Fletcher Roberts is well aware of his importance to the Western Bulldogs' premiership aspirations.

The 196cm, 90kg Roberts has the physical attributes to contain the League's monster forwards.

While he is still developing and injuries have slowed his progress, the former Sandringham Dragon knows he is yet to cement his spot in the finals-bound Bulldogs team after five seasons and 29 games at Whitten Oval.

"I've been around the mark as a key defender for a couple of years now," he told AFL.com.au.

"I spoke to 'Bevo' (Luke Beveridge) a couple of weeks ago about how important I can be in our defensive structure and how important depth is at our club. 

"He believes in every one of his players and he's always pumping me with confidence. 

"But I hope in the coming years I can continue to build my tank and work on my strength and speed so I'm able to play on the big boys and the ones that can run a lot." 

Despite having one of the AFL's stingiest defences, the Dogs will need a few key options to combat the array of key forwards they will confront come September.

With the ever-reliable Dale Morris better suited to smaller forwards in the twilight of his career, it will be left to Roberts and first-year sensation Marcus Adams to quell the likes of Adelaide's Taylor Walker, Geelong's Tom Hawkins and Giant Jeremy Cameron.

But with last year's gripping elimination final loss to the Crows still fresh in his mind, Roberts, 23, believes the experience has left him battle-hardened.

'A few times last year and in the final I might have been caught in front, so I think it's just a matter of getting in a more lateral position and being able to jump at the ball, which is one of my strengths," he said. 

"I learnt a lot about the speed and high-pressure situations in games, so the more we play in those really close games the more we'll be able to handle those situations. 

"As a defence we're starting to work well together from the start of the year and we pride ourselves on the way we defend.

"We call it an 18-man defence and if we don't have that we struggle to play our best footy."

Saturday night's game against St Kilda will be the perfect preparation for what awaits the Dogs in the finals, with the Saints possessing three strong marking targets in Josh Bruce, Tim Membrey and evergreen skipper Nick Riewoldt.

Roberts is expecting to become familiar with that imposing attack in the next few seasons.

"They've got some great forwards in Bruce, Riewoldt, Membrey and Paddy McCartin when he plays," Roberts said. 

"The sides have played some exciting games and they're the matches people come and watch. 

"Both teams are young with a lot of talent, so I think it will be a strong rivalry for the years to come."