It's American Idol vs. The Voice all over again.

With 12 seasons already under its belt in just six years, The Voice has proven itself a force to be reckoned with in the reality singing competition world, giving stalwart American Idol a run for its money. Now, as Idol prepares for a return to the airwaves on ABC, an epic battle already appears to be brewing.

WATCH: Kelly Clarkson Joining 'The Voice' as Season 14 Coach 

Idol favoritesJennifer Hudson and Kelly Clarkson have each signed on as coaches for The Voice's upcoming 13th and 14th seasons, respectively, essentially nixing any possibility to return to the show that made them famous. This just days after reports surfaced that Idol producers were interested in wooing Clarkson to serve as a judge on its reboot. 

"I always thought if they could get Kelly it would be a big deal," Simon Cowell said, indulging his urge to throw a dig at his former show. "And then I thought Jennifer Hudson -- she's going to The Voice -- and then I thought, William Hung! He'd be great."

Meanwhile, Idol season 13, 14 and 15 judge Harry Connick Jr. is thrilled for Clarkson's new opportunity.

"She's amazing," he gushed. "She's, like, the perfect person to judge on a show like that because she knows both sides. What it's like to have hits and what it's like to be in a competition. She's going to be amazing." 

Cowell, who currently serves as a judge on America's Got Talent, has confirmed that he won't be returning to judge Idol, but the door appears to still be open for longtime host Ryan Seacrest.

"I don't know, we're still talking about it. I read the GRAMMYs we're coming to New York," Seacrest, who now co-hosts Live With Kelly and Ryan in New York City, told ET earlier this week. "I was like, 'Gosh, this would be an easier conversation if Idol was in New York,' but it's not my decision."

For more on that, watch below.

WATCH: Ryan Seacrest Weighs In on Kelly Clarkson As an 'American Idol' Judge