We caught up with the girls at Wembley Arena today to talk about the final and their plans.
However other than confirming the fact taht they were singing together, the pair were giving NOTHING else away.
Louisa teased: "We've got it covered, don't worry about that, but we're not saying anything."
Rita raved about singing with the teenager: "I'm so excited, it's the best way to round off of these crazy months."
"It's going to be so cool!" enthused Louisa.
However the duo are saving their voices for Saturday night with Rita adding: "We're both whispering right now because we're on voice rest".
Meanwhile, Rita called on fans to support the 17-year-old and insisted Louisa was NOT safe despite being the huge favourite to win.
But the newbie X Factor judge also suggested that whatever happens this weekend, Louisa's future looks bright.
"Obviously winning is great but I don't think it's the most important thing in the world," Rita explained. "I want to be clear here when I say even though she's the favourite, and this and that, she's still not safe and every vote is really important for us and we really need that support so Louisa can win the show...
"But I don't think it's the last time you're going to see Louisa Johnson."
The X Factor 2015 final airs this Saturday and Sunday night on ITV from 8PM.