The battle for the No. 1 position on Billboard magazine's pop album chart was supposed to be between Michael Jackson's "Bad" and Bruce Springsteen's "Tunnel of Love," which beat out "Bad" last week. No one was prepared for an end run by the "Dirty Dancing" sound track, which sneaked by the pop heavies and took over the top spot. The sound-track album is getting a boost from the Bill Medley-Jennifer Warnes duet single "(I've Had) the Time of My Life," which is No. 3 on the pop singles chart and may inch to No. 1 next week. Richard Marx's first solo album, "Richard Marx," (No. 23) has been one of the enduring hits on the pop chart. Belinda Carlisle's "Heaven on Earth" (No. 24) is one of the fastest-rising albums on the pop chart. Hot pop single: Cutting Crew's "I've Been in Love Before" (No. 12).
* Sixteen-year-old Tiffany is the newest pop sensation. Her single "I Think We're Alone Now" has been No. 1 on the pop chart for the last two weeks. Her album, "Tiffany," climbed seven notches to No. 28.
TITLE RANK RANK WEEKS LAST 2 WKS ON WEEK AGO CHART 1. Dirty Dancing 3 4 9 Soundtrack (RCA) 2. Tunnel of Love 1 3 4 Bruce Springsteen (Columbia) 3. Bad 2 1 8 Michael Jackson (Epic) 4. Whitesnake 4 2 31 Whitesnake (Geffen) 5. A Momentary Lapse of Reason 5 5 8 Pink Floyd (Columbia) * Tiffany 35 44 8 Tiffany (MCA)