This could be the biggest toss up in American Idol history.   Who will win, Jordin Sparks or Blake Lewis?

Even Simon Cowell can't predict it!  Cowell says this season's Idol has come down to a "brilliant entertainer" and a "great singer."

"I can't call it at this stage," Cowell told reporters on a conference call. "For Blake, he's a brilliant entertainer, but the negative is he's not a fantastic singer. The advantage for Jordin is she is a great singer and the negative is she hasn't done one performance yet which I can remember as a 'wow.'"

Jordin Sparks, a smiling 17-year-old with huge voice, and spiky-haired Blake Lewis, 25, who puts a modern twist on classic songs, will square off in the two-part finale on Tuesday and Wednesday.