"I'm going to say he's the favorite, but what do I know?" the "Idol" judge told Jay Leno on NBC's "Tonight Show" on Monday.
Cowell had earlier predicted that rocker Chris Daughtry, who was booted off "Idol" in an upset last week, would be among the show's three remaining finalists.
Instead, along with the 29-year-old Hicks, an Alabama native, the remaining contestants on the Fox program are sultry crooner Katharine McPhee and Elliot Yamin.
Cowell expects Yamin to be the next to go, resulting in a Hicks-McPhee finale on May 23-24. Though Cowell thought McPhee, 21, should have been voted off last week, he thinks she'll last one more round.
"Based on last week, absolutely she should have gone," said Cowell. "But, you know, she's got a fighting chance. I think she'll make the final, and I'll tell you why: because I'm choosing one of her songs this week."
The 27-year-old Yamin might not have Cowell's vote, but he has a fan in judge Paula Abdul.
Last week, Abdul told Teen People magazine, "I am going to be honest with you — I want Elliot to win."
After performances Tuesday evening, the remaining "Idol" field of three was to be cut to two on Wednesday (9 p.m. EDT). The winner will be crowned May 24.