While we don't know what Jack sings, Delta is very Delta, screaming, "Jack!"
"What a voice!"
Meanwhile, Guy Sebastian looks like he is ready to battle.
Jack then explains in the clip, "I haven't been on a stage in over five years."
"I'm not little Jack Vidgen anymore."
Looks like that's going to change.
Speaking out about returning back onto our screens, Jack joked to New Idea that he hoped to turn more than just the judges' chairs.
“Hopefully I’ll find a husband,” he laughed.
“No, I’m happy and single. I’m just so grateful for this opportunity and to be let back into people’s lounge rooms and share my story.”