After 125,000 nationwide auditions and months of nail-biting eliminations, Alaina and McCreery will woo "Idol" judges and some 25 million fans with three songs each in the hope of winning a guaranteed recording contract.
Alaina, 16, from Georgia who has dreamed of appearing on the show since age 6, is the youngest person to reach the finale; McCreery, 17, from North Carolina, has a deep voice that belies his youth and has barely put a foot wrong.
But whichever contestant prevails when the votes are announced on Wednesday -- and predictions as usual are for a close race -- country music may end up the real winner, some experts say.
"Either way they have two people who could do very well in country music. If you look at some of the biggest sellers of the past couple of years they have been Taylor Swift, Lady Antebellum and Miranda Lambert," said Yahoo! Music managing editor Lyndsey Parker.
Swift has sold more than three million copies in the United States alone of her November 2010 album "Speak Now".
Searches on Yahoo! for "American Idol finalists" have spiked 949 percent this week ahead of 10th season climax of the most-watched TV show in the United States.
Alaina is getting nearly nine times as many searches as McCreery, according to Yahoo! data. But that doesn't guarantee that "Idol" is about to crown its first female winner since Jordin Sparks in 2007.
SEARCHES VS. VOTES
"People who are searching are not necessarily the people who are voting," Parker said, recalling that searches for 2009 finalist Adam Lambert far surpassed those of eventual winner Kris Allen.
Media measurement technology firm General Sentiment however found that McCreery was winning the social media buzz war, generating 30 percent more discussion online than Alaina in the last five days.
"I do think Scotty is going to win, but I think it will possibly be the closest race in history of 'Idol'. And although Lauren will probably come in second, she will probably sell more records than Scotty," Parker said.
"She has more crossover appeal in the type of country she does, and even though boys tend to win on 'Idol', girls are dominating the real pop market place right now." she added.
Country singer Carrie Underwood, who won "American Idol" in 2005, is the contest's top earner with 12.2 million albums sold and a clutch of Academy of Country Music awards.
"American Idol" also has plenty to celebrate after its first year without caustic British judge Simon Cowell. After four years of falling ratings for broadcaster Fox, the overall audience is up four percent this year at 24.8 million regular viewers.
That's partly due to a shake-up on the judging panel that brought in Jennifer Lopez and Aerosmith frontman Steven Tyler to join veteran Randy Jackson -- and with them a kinder, more supportive vibe.
After dismal sales for recent "American Idol" champions, record company Universal Music will be hoping that Alaina or McCreery can work some country music magic on their post "Idol" careers.