It's the follow-up to Lamar's Grammy-winning, Billboard 200 chart-topping hit To Pimp a Butterfly.

The new album apparently includes untitled songs he performed at the Grammys last month, on The Tonight Show Starring Jimmy Fallon in January and another on Comedy Central's Colbert Report in 2014.

Judging by the track titles -- which are all "untitled" with a number and what appears to be a date following -- Lamar seemingly recorded these songs between 2013–2016.

View tracklist below.

Untitled Unmastered track list:

1. "untitled 01 08.19.2014."2. "untitled 02 06.23.2014."3. "untitled 03 05.28.2013."4. "untitled 04 08.14.2014."5. "untitled 05 09.21.2014."6. "untitled 06 06.30.2014."7. "untitled 07 2014 – 2016"8. "untitled 08 09.06.2014."

On Tuesday, Lamar's manager and label head TDE CEO Anthony "Top Dawg" Tiffith announced he would be releasing a new project in the week, but gave no hint it might be new Lamar songs.

“I’ve decided 2 drop a project 1 day this week. I won’t say…,” he said. A follow-up Twitter post from TDE also said Lamar’s fans should thank NBA superstar LeBron James for the album release.

In an interview with grammy.com and 2 Dope Boyz last month, the grammy award winning rapper revealed he has a “chamber” of unheard material that didn’t make his album cuts.

“You see all these performances on these late night shows — I got a chamber of material from the album that I was in love where sample clearances or something as simple as a deadline kept it off the album,” he said. “But I think probably close to ten songs that I’m in love with that I’ll still play and still perform that didn’t make the cut.”

‘’Untitled Unmastered’’ is Lamar’s fourth official album, and if things go his way, it might be another number one for him. Last year, he released ‘’To Pimp A Butterfly,’’ which went on to be certified platinum, won several Grammys (including Best Rap Album), and wound up as the most critically-praised title of the year.

His debut smash, good kid, m.A.A.d. city, made it to number two on the Billboard 200 back in 2012, and a lesser-known album entitled Section.80 failed to chart back in 2011 before he made it big. The collection is a welcome surprise for Lamar’s fans, who weren’t expecting new music for some time, as the promotion of Butterfly only recently died down.

Kendrick’s is just the latest surprise (or semi-surprise) album release in the hip-hop space in the past few years. Plenty of big names have used the marketing tactic lately, and it has been met with praise, commercial success, and delight from fans, many of whom appreciate being shocked with new tunes. In 2015, both of Drake’s chart-topping albums (If You’re Reading This It’s Too Late and What A Time To Be Alive) came with little or no warning, and just last month rapper Future (who joined Drake on Alive) scored his third number one album in just even months when he released EVOL with very little warning as well.

View album artwork

Buy the album on iTunes here or stream it on TIDAL and Spotify.

Watch video of Lamar perform on 'The Tonight Show' below.