NEW YORK: A surprise new album by Kendrick Lamar opened Sunday at number one on the US chart in the latest triumph for the critically acclaimed rapper.

The album — the fourth by the 28-year-old, entitled “untitled unmastered.” — sold 178,000 copies or the equivalent in streaming in the United States in the week through Thursday, Nielsen Music said.

Lamar released “untitled unmastered.” without previous notice on March 4 in the wake of the Grammys, where he was the music industry gala’s biggest winner with five awards.

He characterized the album as a series of rough works from the studio, although the songs take on heavy themes including an opening track that mixes images of the biblical apocalypse and contemporary social ills.

Lamar also went to number one in 2015 with “To Pimp a Butterfly,” a reflective look at the state of black America that experimented with jazz elements, which are also apparent on “untitled unmastered.”