Already missing Alex Johnson for the season, the AFL's best performed and most cohesive backline from 2012 will now be without the influential Shaw for its biggest test of the new campaign.
It will only be the third match Shaw has missed in four seasons at the Swans.
Following regulation victories over expansion clubs Greater Western Sydney and Gold Coast, the Swans will need to up their game against a Kangaroos outfit that has shown good signs so far this year.
Led by Drew Petrie and Coleman Medal frontrunner Lindsay Thomas, the Roos have a variety of attacking weapons, but Mattner believes the Swans have enough cover for their depleted defence.
"Rhyce has been ruled out and won't train today, hopefully we get some young guys (back in) like Dane Rampe and Tony Armstrong, who have been playing well in the reserves," Mattner said on Thursday.
"AJ (Johnson) has been a big loss, but LRT (Lewis Roberts-Thomson) has come back and filled that spot pretty well and we've been lucky to have LRT in the team - he can go forward and back or in the ruck.
"We've had a few injuries throughout the pre-season and the back six hasn't really played together, but I think we're starting to gel and get some good results."
As well as the injuries to Johnson and Shaw, Mattner and Nick Smith both had limited pre-seasons due to hip and knee problems respectively.
But they are both nearing full fitness and Mattner believes Smith will get the initial job on Thomas, while he said any of Ted Richards, Heath Grundy or Roberts-Thomson could spend time on Petrie.
"I saw bits and pieces of it at home," Mattner said of North's clash with Geelong last weekend.
"Early they looked really good and then late Geelong just got the better of them and started playing really good footy at the end.
"(North's) midfield is really good and where they got on top early was through their midfield.
"They won the clearances pretty well and their forward line, they've got some tall players but also some smalls. Lindsay Thomas is playing really well.
"They've got Drew Petrie as well as a big target.
"The midfield battle will be the big one, but also our defence will be massive as well."
Having flipped in and out of the team over the past 12 months, Armstrong could be presented with another opportunity to push for a regular place in the Swans' backline.
Mattner feels it is up to the 23-year-old former Crow to take it.
"He's got to take his opportunity when selected," Mattner said.
"This week could be his opportunity.
"If you're not in the team you have to play good reserves footy and he did that last week.
"When you get your opportunity, you have to take it."
Marty Mattner is a defender in NAB AFL Fantasy. He averaged 57.3 points in 2012. Register your team at our AFL Fantasy Hub.
James Dampney is a reporter for AFL.com.au. Follow him on Twitter: @AFL_JD
