Former Stormers lock Roux partners skipper Leo Cullen, while former St. Andrew's College student Marshall, who made his debut for the province away to Ulster in December 2010, comes into the back row alongside Shane Jennings and number 8 Leo Auva'a.
Ireland hooker Sean Cronin is included in the front row alongside Jamie Hagan and Jack McGrath. In the absence of the injured Isaac Boss, John Cooney will link up with Ian Madigan at half-back.
The rest of the largely fledgling backline that started last weekend's game in Llanelli - aside from the experienced Isa Nacewa who will make his 104th Leinster appearance - is set to continue.
Devin Toner, the scorer of Leinster's first try against the Scarlets, has been named on the replacements bench along with South African prop Heinke van der Merwe.
Speaking ahead of the province's return to the RDS, head coach Joe Schmidt said: "There's always more pressure on the back of a defeat, particularly the nature of that defeat (to the Scarlets).
"The players are very aware of that and the coaching staff is, but at the same time there is an expectation from our supporters that a performance like last week will not be repeated this week. I think there's very much an internal expectation that it won't be repeated either."
Asked about the latest injuries picked up in the squad, he added: "Unfortunately we have a few more long-term injuries than we would have liked. Dominic Ryan has ruptured the ligament in front on the top of his ankle and he will be out of play for between 10 to 12 weeks.
"Isaac Boss has done a fair bit of damage to the medial ligament in his elbow and he will be out for between six and eight weeks.
"Aaron Dundon went to the doctor to get stitches over the eye and complained that his foot was sore. It (came to light) he has a fairly severe mid-foot sprain and he will be out for eight to ten weeks."
Ticket sales for Saturday's game have passed the 14,500 mark and are on sale online here. They are also available to buy from the Leinster Rugby Store (Donnybrook) and Spar (Donnybrook) as well as Ticketmaster outlets nationwide.
The Leinster ticket office and van will be open for sales at the RDS from four hours prior to kick-off this Saturday and for all games this season.
LEINSTER (v Newport Gwent Dragons): Isa Nacewa; Andrew Conway, Brendan Macken, Noel Reid, Fionn Carr; Ian Madigan, John Cooney; Jack McGrath, Sean Cronin, Jamie Hagan, Leo Cullen (capt), Quinn Roux, Ben Marshall, Shane Jennings, Leo Auva'a.
Replacements: Tom Sexton, Heinke van der Merwe, Martin Moore, Devin Toner, Jordi Murphy, Luke McGrath, Colm O'Shea, Darren Hudson.