'You should say, 'I can help you get to third place!''
The pair sat down together during Monday's Battle Rounds, where Kelly teasingly called Niall out for disrupting her game in season 23.
"You kind of ruined it a little bit for me, because I'm always the one that's like, 'I've been in a singing competition," Kelly explained, noting that the enticement doesn't work as well this season, because Niall was also famously on a singing competition -- where he got grouped into a little boy band called One Direction.
"And, like, we both won," Kelly continued, but Niall had to interrupt.
"We didn't win," he admitted. "Well, we got a medal..."
"Third place," Kelly interjected, to which Niall fired back, "So you do know!"
One Direction famously came in third on the seventh series of The UK's X Factor -- finishing behind winning singer Matt Cardle and runner-up Rebecca Ferguson -- and while they went on to plenty of success despite it, Kelly wasn't quite ready to let that fact go.
"You should lead with, 'I can help you get to third place!'" she pitched with a laugh.
"I texted him," Kelly shared. "If he was gonna do a last season, I wanted to make sure I was there."
However, the talk show host insisted that she won't be letting nostalgia affect her competitive nature.
"If [Blake] wins, I am very happy for him, because that is super cool to win on the last season and he's literally the show, from its conception," she conceded. "But, like, I'm not, like, rooting for him to win. I'll be happy for him if he does, but I'm obviously trying to win myself."
As for the show's new coaches, Niall and Chance said they were ready to put in the work against the Team Blake dynasty.
"It's been awesome," Chance said of joining the show. "Kelly's very, very sweet, very nice to me. And Blake is... here."
The Voice airs Mondays at 8 p.m. PT/ET and Tuesdays at 9 p.m. PT/ET on NBC.