The former Blue Bulls Head Coach has led team preparations this week for the Dragons as they go in search of a victory against the East Midlands outfit at Franklin's Gardens.
“We’re telling the players to go with the attitude of express yourself and use the opportunity to put yourself out there,” said Marnitz.
“If we look at our performances against the Blues and Ospreys I thought we were outstanding in those two games defensively and we really stuck in. If we’d done a couple of things better then we could have pulled either of those through - the scores were not a fair reflection of how tight the games was.”
Marnitz, the Johannesburg-born former scrum half joined the Dragons in August and has been working alongside Dragons Head Coach Bernard Jackman to develop the talent within the regions' squad.
“System wise and principle wise we’re getting closer to where we want to be,” added Marnitz, ”at home we’re starting to build a fortress, but we need to improve on the road.
“The boys knew we weren’t good enough in Cork, but we also need to understand that if you lose your five best players in the region - and you add Ollie to that - if none of those are available then there’s no illusions that you need to be firing at 100% to survive when you go to Munster and on the day we were a bit cold.
“Northampton will again be a massive challenge for us, we’re going with a very young team and we want to blood a couple of youngsters that are coming through our system, so we know it wont be easy, but we’re looking for an improved performance and we need to build on the Ospreys and Cardiff Blues game.
“We’ve done a fair bit of analysis of Northampton in the Premiership and in the Cup. In the pre-season game we played them they were full strength and we had played Montpellier the previous night so it was vastly different. However, they are strong and it’s another opportunity for our youngsters. It’s going to be a very exciting game.
Wales 7s international Ben Roach and fly-half Arwel Robson make their first starts after being replacements in Cork and there are three debutants – academy prospect Joe Goodchild at full-back, Joe Thomas signed on-loan from the Ospreys and RGC 1404 number eight Huw Worthington, who hails from Penybontfawr.
“We’re really pleased to have five players away with Wales as we want our players to be recognised at a high level and it shows how much they’ve grown.
“For us as a group, we’ve got to grow quickly. We’re a young team as it is, but with five players away on international duty and thirty players not available with injuries included too, we don’t have the resource to fill the void so we are in a bit of a pickle.
“Ben Roach from the Sevens has made a really good impression on us. He’s an exciting youngster who works really hard in training and he’s with us on a temporary basis as his bread and butter is still Sevens, but we’re pleased we have the relationship with them and Ben is looking forward to cutting his teeth in the 15s game.
“We cast the net wide to see what Premiership players we can get in and those that get selected must realise they might not get an opportunity again. The game of rugby is simple, when you get an opportunity, use it. If you don’t, someone else can step up and take their opportunity."
The clash with Northampton Saints starts at 5.15pm at Franklin's Gardens, with the Dragons returning to Rodney Parade to take on the Scarlets next Friday (17 November) in the second round of the competition. CLICK HERE to secure your tickets for the Welsh derby.