These are the rookies ready to step in and fill the void for the Canberra Raiders as the premiership contenders prepare for a heavy travel toll in a revamped NRL season.

Parkes Spacemen junior and NSW under 20s back-rower Darby Medlyn joins versatile forward Kai O'Donnell and teenage prop Ata Mariota in the fold for the Green Machine.

The trio could soon find themselves banging down the door for a start after the club waved goodbye to Jack Murchie [New Zealand Warriors], Luke Bateman and JJ Collins [Queensland] over the past fortnight.

Raiders recruitment guru Peter Mulholland says the rookies enter the fray with plenty of potential but concedes no second tier competition for them to bide their time in makes for a steep learning curve.

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Canberra have a handful of empty slots on their roster which coach Ricky Stuart will use should the right player come along, but for now his focus is on the squad already at hand.

"Rick's idea is we need to promote from within and we had a pretty good 20s squad last year, so he's giving them opportunities," Mulholland said.

"Kids like Matt Timoko and Harley Smith-Shields, Darby, Kai and those sorts, it's really important for them to capitalise.

"They can also watch closely Corey Horsburgh, Bailey Simonsson and Emre Guler, the work those guys have put in to get where they are as quickly as they have."

So what can we expect from this band of Raiders rookies?

O'Donnell can play in the middle, on the edge, and represented Queensland's under 18s side as a hooker, while Medlyn played lock for the NSW under 20s last season.

Middle forward Mariota has turned heads since he came to the club as a package deal with his brother Taulauniuotagoloa Mariota, who made headlines in February as a 115 kilogram teenage prop with the touch of a playmaker.

"[O'Donnell] brings a lot of energy which is really important. That inspires others around the club," Mulholland said.

"When you bring energy into a group like that, the older players need to respond to it as well. It's good for the group.

"Darby is a leader in his own right and he will learn a lot from working alongside the likes of Sia Soliola and Josh Hodgson. He's certainly a little bit of a different player, he's got feet and he is very strong from the hips down.

"He has just got to work on getting bigger. Darbs is probably 12-18 months off where we would like him to be, and not having games this season will probably hinder that development.

"Mariota, potentially very good. He needs to train at the top level, he's a very good kid. He came down to us from Mount Pritchard. I signed him to get his younger brother and he'd only had four games of rugby league.

"He made a great impression in SG Ball and 20s last year, he is only a few days off playing SG Ball again this year, he's not 19 until December. He's 110 kilos, great feet and strong. He's going to learn a lot."

Mulholland concedes the absence of NSW Cup or Jersey Flegg competitions due to the COVID-19 pandemic is "not ideal for their development", but has lauded Stuart's "innovative" approach to replicate game scenarios at training.

Raiders co-captain Josh Hodgson believes Canberra will have to rely on the depth in their squad if they are to go one better and avenge last year's grand final heartbreak.

"I'm sure it will be very testing, especially around that 10, 11, 12-game period where you have another six or seven to go. You have to rely on the depth of your squad a little bit more," Hodgson said.

"It's good to see a few kids probably going to get a chance this year, when it may not have happened because we have to rely on some players in our squad that weren't expecting to get a crack this year."