VIDEO: Ailing Lauren Alaina Emerges As Frontrunner In American Idol Grand Finale

In the final performance of the evening, she dug deep in belting out the original ballad Like My Mother Does, prompting judge Jennifer Lopez to tell her, "Lauren, with that song, you may have just won!

McCreery got big props from judge Randy Jackson for his song I Love You This Big, as Jackson was impressed with the teen singer's range, noting he was able to seamlessly transition between singing "really low and really high."

Alaina also sang Carrie Underwood's Flat on the Floor and Pam Tillis' Maybe It was Memphis (selected by her idol Underwood). McCreery also sang Montgomery Gentry's Gone, and Check Yes or No, a song chosen by -- and straight from the catalog of -- his idol, country legend George Strait.

Prior to his performance, McCreery, a Garner, North Carolina native, looked back on his journey from hopeful to household name.

He tweeted, "man, it feels like just yesterday i was up in milwaukee for the show's auditions, butterflies flying, about to sing baby lock them doors for the judges. #showtime."

If Alaina, a Rossville, Georgia native, prevails Wednesday, she'll be the show's youngest-ever winner (Jordin Sparks won 2007's competition at 17).

Alaina tweeted Tuesday: "Thanks to all my fans for voting. Y'all are the best. Y'all have been so loyal to me. I'm blessed to have fans like you guys. Love ya."

If past performances bear any indications, McCreery has never finished in the bottom, while Alaina found herself there three weeks ago.

The show’s tenth season -- the first without Simon Cowell -- has been a memorable one for a few reasons: the amazing talent among the competitors (the finalists, James Durbin, Jacob Lusk, Pia Toscano and others), and the refreshingly rebuilt panel of judges (Jennifer Lopez, Steven Tyler and Randy Jackson).