Life has changed dramatically for Susan Boyle in the past six months

Susan Boyle is locked in an unlikely battle with former Take That star Robbie Williams for Number 1 album.

Both Susan and Robbie are in America this week to plug their albums and the clever money is on Susan.

Susan has already sparked "Boylemania" in the U.S. after her stunning performance on America's Got Talent.

Singing on the American version of the show which made her a star, Susan performed to an estimated 25 million viewers.

Her version of the  Rolling Stones hit "Wild Horses" from her debut album was an inspired one.

Her album, "I Dreamed a Dream," which won't even be available until Thanksgiving, surged back to the top of the Amazon charts ahead of Whitney Houston and the Beatles.

This is some achievement given the publicity about the Beatles and Whitney.

The remastered Beatles have been all over the radio stations with critics divided over the album while Whitney has been all over the tabloids after her revelations on the Oprah talk show.

Meanwhile, Susan and Robbie will both release their albums within weeks of each other.

The legendary British music critic Paul Gambaccini says Susan will win.

"No contest. It is Susan Boyle," he said.  "That is not an insult to Robbie Williams... Boyle is the new-artist story of the year around the world. The interest factor alone will bring her many, many sales."

The Robbie Williams album, "Reality Killed the Radio Star," will be released two weeks ahead of "I Dreamed A Dream."

This is Robbie's last chance for an American breakthrough and some critics say Robbie is shooting himself in the foot by trying to compete with Susan.

As Gambaccini says, 120 million people have watched Susan on YouTube. "Even if only one in 10 people who has watched her buys the album, we are talking ridiculous numbers. No one can stem that tide. She has the whole international Simon Cowell Machine behind her."