The Black Eyed Peas are back with a brand new single, titled "Yesterday."

Lead singer Fergie is not present "Yesterday," which debuted today exclusively on Apple Music. The hip-hop group released the song to celebrate their 20th anniversary. It is unclear why Fergie is not in the song or its respective music video.

It's likely that the pop singer didn't have time as she is currently putting the finishing touches on her upcoming second solo album, according to The Daily Mail. Fuse is speculating that the Peas wanted to celebrate their 20th anniversary without Fergie because she wasn't originally in the group when it was formed in 1995. She joined in 2002.

"Yesterday" samples a handful of old hip-hop songs like the Beastie Boys' "Paul Revere," ODB's "Shimmy Shimmy Ya" and N.W.A.'s "Straight Outta Compton."

"We're paying homage to the folks that inspired Black Eyed Peas," will.i.am said in an interview with Apple Music's Beats 1 radio station. "The video is a visual version of [the song]."

The Black Eyed Peas' new album will be released later this year.

Image via INFphoto.com.