Dragons enjoyed a 54-17 win over Timisoara Saracens in Round 1 while Northampton Saints lost 41-20 on home soil to Clermont.
However, Marnitz has warned against reading too much into Northampton’s loss to the French giants as the Saints prepare to head to Wales.
“Northampton have a very powerful game and maul very well,” he said.
“They had a difficult run against Clermont, but they (Clermont) are a world class team.
“Clermont, for us, is not an indicator of where Northampton are. No team has been able to cope with them in France, they have steamrollered people and even picked up away wins.
“If you look at squad on paper, they could pick three teams that could possibly compete in Top14.
“We’ve played Northampton once in pre-season so have done our homework. We know we have got to be physically up for it as well as the mental side.
“They have come off a loss and they will be keen to fix things. We have got to be ready for that challenge.”
Dragons only returned to Wales late on Sunday evening and have had a quick turnaround before Round 2 on home soil.
However, Marnitz insists the mood in camp is strong and buoyant after the bonus point win in Romania on day one.
“It was a long trip to Romania and long trip back. The boys had Monday to recover and a heavy day on Tuesday,” he said.
“We have put them through the mill and we can’t waste time this week - because we don’t have it.
“Winning is never a bad thing and putting up 50 points was good for us in Romania.
“The boys are buzzing. We had loads of sunshine and a win; there are no complaints in the camp at the moment.”
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