The youngest-ever finalists --
, 16, and
, 17, -- take the stage for the two-night finale, beginning Tuesday, May 24.
In a half-hour interview the only time executive producer
is quiet -- and looks genuinely perplexed -- is as he considers which teenager will be crowned Season 10's
"If Scotty wins, I believe he could be the biggest 'American Idol' selling artist of all time," Lythgoe tells
"Whoever it is, the fact is, it's America's vote."
But when you have had a season with a diverse array of artists, where will the
Jacob Lusk and
Paul McDonald fans shift their alliance?
"I don't know who James' votes will go to," Lyhtgoe says of
James Durbin, who left two weeks ago. "I don't know who a rocker votes for in who's left. I truly don't know. You've got two country [singers] there."
Lythgoe does remain impressed by
Haley Reinhart, who made it to the Final 3 despite numerous appearances in the Bottom 3.
"I don't know what Haley's genre was," he says. "She doesn't have a genre. She's slightly old-fashioned, slightly jazzy, but if you take her individual tracks off of iTunes, she sounds very much like Adele."