Legendary singer Paul Anka received quite a shock, when along with millions of other Michael Jackson fans, he listened to the late singer's new single "This is It" on Monday. It turns out it wasn't the first time he had heard the song - in fact, he wrote the song with Jackson in 1983. The 68-year-old Anka, who will be performing in Israel for the first time at the Nokia Center in Tel Aviv on November 18, wrote the song with Jackson for a 1983 duets album. Originally titled "I Never Heard," the song appeared on an early 1990s record by a singer named Sa-Fire with a co-authored credit for Anka and Jackson Anka, who has dozens of hits to his credit both as a performer ("Diana," "Having My Baby") and as a composer ("My Way," the theme to the Tonight Show) said Jackson's estate moved quickly to give him credit, promising him 50 percent of the song's profits. "They did the right thing," Anka said. "I don't think that anybody tried to do the wrong thing. It was an honest mistake." The string-backed ballad was released on the singer's official Web site and sent to radio stations. It gives advance publicity to a documentary, culled from footage of Jackson rehearsing for the concerts that he never got a chance to do. Representatives of Jackson's estate acknowledged Anka's work in a prepared statement. Until Anka stepped forward, the song's history was a mystery. "The song was picked because the lyrics were appropriate because of the name Michael gave his tour," the statement read. "We are thrilled to present this song in Michael's voice for the first time, and that Michael's fans have responded in unprecedented numbers." Anka told The Jerusalem Post the day before the song was released that despite his 50-year career, he still considered himself a relevant performer and songwriter. "You never stop having to prove things to yourself," he said. The full interview with Anka will appear next week.