Billboard's first look at some of the top contenders in the biggest categories at the 68th annual Grammy Awards.

Lamar's duet with SZA samples Luther Vandross' 1982 hit "If This World Were Mine." The song was written by Marvin Gaye, who himself recorded it in 1967 as a duet with Tammi Terrell.

Kendrick Lamar and SZA's "Luther" leads the Billboard Hot 100 songs chart for an eighth total and consecutive week. The single, whose title celebrates late R&B legend Luther Vandross, who is ...