14th May 2019, 15:00 | catalans
The French club took up an invitation from Barcelona president Josep Maria Bartomeu to play a game at the 99,354-capacity stadium after parading the Challenge Cup there in September.
The fixture has generated enormous interest and McNamara, the former England coach, says it will create reverberations around the world.
"It's probably a once-in-a-lifetime opportunity for both ourselves and Wigan," McNamara told a press conference in Perpignan.
"The Nou Camp is iconic throughout the world and if you are from the Catalan region it's even more special.
"I'm sure there will be international recognition from Australia, New Zealand and other parts of the world and it's about maximising that publicity for our game.
"For us as coaches and players, it's not just about turning up there and playing the game, it's about putting a spectacle on.
"It's about playing really well and showing the people who are exposed to it for the first time just what a good game it is."
Both McNamara, who was involved in the Magic Weekend as Bradford coach, and the Dragons are no strangers to 'on the road' games and the Catalans drew a crowd of 18,150 for a Super League game against Warrington at the Olympic Stadium in Barcelona in 2009.
With the Catalans having already passed 20,000 ticket sales and Wigan expected to take 5,000 fans, the current Super League record crowd of 25,004 set for the derby between Wigan and St Helens at the DW Stadium in 2005 is sure to fall.
"We've sold plenty of tickets and everybody I speak to back in England, whether they're a Wigan fan or just a rugby league fan, are really keen to get across," McNamara said.
"We're on track to break the record. Barcelona are working hard to promote the game and I know our club have made every effort we can to get our fans there from different parts of France."
Just 4⃣ days to go till @WiganWarriorsRL take on @DragonsOfficiel at the Nou Camp!— Wigan Warriors 🍒⚪️ (@WiganWarriorsRL) May 14, 2019
If you're coming along to support the 🍒⚪️, make sure to share your experience on Twitter with our hashtag #ViscaElWigan
In addition to waving the flag for rugby league, valuable league points will be at stake and McNamara admits his side will be out to atone for a 42-0 defeat at Wigan in March.
"Probably the biggest disappointment for us this season has been the size of a couple of losses that we've had," he said.
"You are never going to go and win every single game but it's how you lose those games and the manner in which we've lost really hurts us.
"Wigan was one of those. We were embarrassed that day. We went there with good intentions but we didn't perform. It's the first time we've met them since and we obviously want to put that straight."
The Dragons have an injury doubt over former Wigan half-back or full-back Sam Tomkins, who has played every game since joining them at the end of last season.
"He had a little bit of a back spasm against Doncaster, but he's improving every day," McNamara said.
"Sam is very professional and he's going to give himself every chance."