The Rua have praised Westlife's "amazing" fanbase for being so welcoming and passionate on tour.
The 'Gasoline' hitmakers - made up of siblings Roseanna, Alanna and Jonathan Brown - are currently on the road with the 'When You're Looking Like That' band, and they have been blown away by the connection the boys share with their audience.
Speaking exclusively to BANG Showbiz, they said: "Oh yeah, it's amazing. There are people who've gone to every single show. It's such a wide range of audience as well.
"There are some kids there, there are some older ladies - and gentlemen! All there singing away. There was a guy yesterday that had flown from Brazil to see them. It's like, from Brazil?! Their tour doesn't go out that far so he had to fly in to see them.
"So their audiences are amazing - and so open to listening to new music, which is great for us as an opening act. They've responded really well to our stuff, which is wonderful."
This week is a dream come true for the trio, who are set to play three nights with Westlife at London's O2 Arena, and they will be joined by their family and friends who - due to the group's greater success in the US compared to closer to their hometown of Windsor - haven't had the chance to see the perform before.
Asked if they'll have a crowd of familiar faces supporting them at the famous venue, they added: "We do, we have quite a few friends and family. We're mainly in America, so this is the first time some people are seeing us play and it's like the O2, it's not a pub gig."
The trio have all had their fair share of experiences acting too, with all three of them appearing as students in the 'Harry Potter' film franchise amongst other roles.
And the siblings admitted while their focus is on music, they are always open to "other opportunities".
They said: "Never say never, if anything popped up we'd sort it in our schedule. If opportunities come up, you've gotta say yes to it. You can't live with regret. Music's the main thing, but we'd definitely have a think if other opportunities came up."