Michael Jackson [ tickets ]'s new single, "This Is It," was released Sunday (10/11) night and almost immediately spawned discussions about its similarities to a 1991 track written by Jackson and Paul Anka and recorded by R&B singer Safire, according to The New York Times.

The following day, Anka said he had not been contacted about the use of the song and was not given proper writing credit for the single, which lists Jackson as the sole songwriter. Anka told the newspaper, "They have a major, major problem on their hands. They will be sued if they don't correct it."

Anka claims "This Is It" is the same song as the Safire cut entitled "I Never Heard." According to the NYT report, aside from a few major differences in the lyrics, the composition is almost identical to "I Never Heard," which Jackson wrote and recorded with Anka in 1983.

The song, originally intended as a duet for Anka's album "Walk a Fine Line," was never released. Anka reportedly claims Jackson took the master tapes and Anka had to threaten the pop superstar with a lawsuit to get them back.

John McClain, a record executive and producer whom Jackson named in his will as an executor, told the media that "This Is It" was based on a tape Jackson left behind containing only his piano and vocal. McClain said he built a full arrangement around it, including backup vocals by Jackson's brothers.

McClan reportedly called Anka on Monday (10/12) to apologize, saying that he had not known that he was one of the authors of the original song, and that Anka would receive all due credit and royalties.