The two advanced at the weekend after the elimination of initial favourite Danny Gokey and on Friday night will vie to become the eighth Idol champion.
Emerging from the crowd as a judges' and audience favourite in the very early days of the audition episodes, Gokey was propelled to the front ranks of the competition by his powerhouse rock-blues vocal style and effusive personality.
His Idol journey was also marked by the shadow of grief: It was revealed in the auditions that Gokey's wife had died just before he tried out.
Gokey spoke of his American Idol bid as a homage to her memory; his performances often ended with the singer curling his hands into the shape of a heart, a gesture seen by many observers as a call to his lost partner.
On stage however, Gokey seemed the most buoyant of spirits.
For weeks, a Gokey showdown with pop phenomenon Adam Lambert was spoken of as inevitable.
Ultimately, however, that destiny was undone by the surprise emergence of Kris Allen, the soft-spoken, folksy singer who has been referred to as a dark horse.
Although the low-key Allen never appeared to threaten the season's two giants, he steadily turned in impressive performances.
On Saturday, with a cliffhanger top three in the balance, he gave what might have been the strongest outing of the night with his pared-down, soulful version of Kanye West's Heartless.
After Saturday's show, the two finalists flipped a coin to decide position in this week's performing finale.
Allen won the toss and, given the choice, elected to have Lambert lead off in the final battle. - Los Angeles Times American Idol is decided in a three-hour finale on Friday at 7.30pm on TV2. - Richard Rushfield.
