Scarlets captain Matthew Rees says the Welsh regions' form in Europe can boost Wales as they look forward to the 3 December clash against Australia.
Newport Gwent Dragons, Cardiff Blues, Scarlets and Ospreys made history by being unbeaten in the first two rounds this season's European games.
Rees said: "It can only benefit us and, obviously, Wales as well."
But coach Nigel Davies has told Scarlets not to get carried away with their win at Northampton.
Rees had to relinquish his role as Wales captain when a neck injury ruled him out of the World Cup, but he hopes to return to face Australia in December and has set his sights on reclaiming the captaincy from Sam Warburton.
And the hooker, speaking ahead of the Ospreys' 26-26 Heineken Cup Pool Five draw in Treviso, said: "The regions are playing some good stuff at the moment.
"At the moment we're on the up and it's important that we don't get too far ahead of ourselves, just keep on working hard and I'm sure that everything else will happen."
Scarlets coach Davies added: "It's got to be pretty big [to win] against a side of Northampton's quality.
"I don't think they'd lost at home in the competition since 2007, so it was a big scalp for us.
"But we've just got to keep our feet on the ground.
"We've just got to take every match as it comes and build the momentum.
"From my point of view the big thing this year has been about belief and believing they [Scarlets' players] can come to places like this and on the back of a result like that, we'll certainly build that belief."
Davies admitted the Scarlets rode their luck in the win at Franklin's Gardens as the Saints gifted them some try-scoring opportunities.
"We had a little bit of luck as well, which we need on occasions," said Davies.
"But I really fell we went at them from the first whistle. We knew we had to do that.
"I thought we dealt with the set-piece very well, which was a problem for us last week [in their win against Castres] and the prep this week has been spot on.
"And we had to play a very good game to get a win... and that's what we did.
"The tries we scored were opportunist, but our game without the ball was fantastic."