When NBC’s all-ages, all-skills competition “America’s Got Talent” returns for a fourth season on Tuesday it has a pretty high bar to clear, one that stretches all the way across the Atlantic Ocean.

Thanks to the online video site YouTube.com, just about anyone with a computer and an Internet connection can view the contestants in the show’s U.K. sibling, “Britain’s Got Talent.”

In June 2007, shy, unprepossessing Welsh mobile-phone salesman Paul Potts took the world by storm with his stirring rendition of the operatic aria “Nessun Dorma.”

Then America fired back with insurance salesman Neal E. Boyd, who came on “America’s Got Talent” last summer and wowed the crowd with his own rendition of the Puccini classic – eventually, like Potts, going on to win the competition.

In April, Susan Boyle, an unstylish, 47-year-old Scotswoman with frizzy hair, a wicked wit and a knockout voice, set the world afire with her rousing and surprising audition singing “I Dreamed a Dream” from “Les Miserables.”

Boyle made it through to the finals, where she performed the song once again. She may have come in second to a dance troupe, but she remains first in the hearts of millions around the world – and reportedly brought a tear to the eye of tough-minded judge Simon Cowell.

Cowell wasn’t the only one moved by the performance, according to Piers Morgan, Cowell’s fellow judge, who’s also on “America’s Got Talent” along with fellow judges Sharon Osbourne and David Hasselhoff and host Nick Cannon.

“At the time,” Morgan says, “I was getting quite emotional, and that’s never happened to me before on any of these shows.”

Of course, now it’s up to the American show to meet that standard.

If you think a middle-aged, unemployed church volunteer who lives alone with her cat, Pebbles, is an unlikely candidate for superstardom, Morgan promises to introduce NBC viewers to someone with an even more unusual story.

“We’ve had two extraordinary moments,” Morgan says. “One was a chicken hunter, a guy called Kevin, who came on, said he’d caught 8,000 chickens himself in one night, clutching four at a go in one hand.

“We were all laughing at him. He was laughing, baseball cap the wrong way around, and he had on a checked farmer shirt. ‘What are you going to do?’ ‘I’m going to sing for you a bit of Garth Brooks.’

“Then he sits down, gets a guitar, starts to sing Garth Brooks, and within about half a minute, the audience was starting to cry. He had the most powerful, emotional voice I’ve seen on ‘America’s Got Talent’ in a long time. Amazing.”