LOS ANGELES - Sam Smith on Sunday won the Grammy for Song of the Year for "Stay With Me" - his second win among the four most prestigious categories on the music industry's biggest night.
The 22-year-old singer, who was virtually unknown a year ago, has enjoyed a global following thanks to the tender ballad about a one-night stand.
Song of the Year recognises the best songwriting, not necessarily performance.
Smith earlier won for Best New Artist.
"I'm having a really, really, really good night," Smith said as he accepted the Song of the Year award, before turning over the stage to his co-writer Jimmy Napier.
As his star rose, Smith quietly added Tom Petty to the writing credits on "Stay With Me" over the similarities in vocal delivery to the rocker's 1989 hit "I Won't Back Down". Smith, who was born in 1992, said he was unfamiliar with the song and Petty said he had no hard feelings, believing the resemblance was an accident.
But the "I Won't Back Down" authors were not considered among the winners of the Grammy, as the Recording Academy considered the song an inspiration rather than part of the composition.