And there have been signs Boyle is feeling the heat.
She lost her cool this week during a confrontation with two reporters, and the police intervened. One contest judge said she contemplated pulling out of the competition to soothe her frazzled nerves.
And her competition isn't giving up without a fight: The Sun tabloid carried a front page picture of young Hollie Steel, who pulled at viewers' heartstrings when she burst into tears in the middle of "Edelweiss" from "The Sound of Music." In an unusual move, she was allowed to redo the song, and the cherubic 10-year-old will be among those joining Boyle in the finals.
It would take "a heart of stone" not to have given Hollie a second chance, judge Piers Morgan told the BBC when challenged about the decision. "What are you going to do? Drive her off the stage when that happens?"
Boyle still remains the odds-on favorite - British bookmaker William Hill said it was offering 10-11 odds on her victory Saturday. The betting service had briefly lowered its odds on Boyle when the reports of erratic behavior seemed to show "there might be a chink in her armor," according to spokesman Rupert Adams. But he said William Hill "got absolutely hammered" with bets and quickly went back to predicting a Boyle victory.
"Britain's Got Talent" has mesmerized Britain all week as a bizarre range of competitors vies for Saturday's finals. The winner, to be announced at the end of the show, will earn a 100,000 pound ($159,000) prize and a chance to perform before Queen Elizabeth II at the Royal Variety Show.
The final won't be shown live in the United States, or streamed over the Internet
- meaning U.S. fans will have to rely on video sharing sites like YouTube, where videos will be posted by the show's producers once it ends Saturday evening.
Boyle sailed through her last test - a performance Sunday of "Memory" from "Cats"
- although she started poorly and did not seem to captivate the audience as much as in her first round.
Voters could swing to Hollie, or to 12-year-old soul singer Shaheen Jafargholi, or teenage heartthrob Shaun Smith.
