An unlikely battle is brewing for the No. 1 slot on the next Billboard 200 albums chart. Sturgill Simpson’s new A Sailor’s Guide to Earth and Rihanna’s Anti are both eyeing the top of the tally, as industry forecasters suggest both sets could earn somewhere around 45,000 equivalent album units in the week ending April 21.

The Billboard 200 chart ranks the most popular albums of the week based on multi-metric consumption, which includes traditional album sales, track equivalent albums (TEA) and streaming equivalent albums (SEA). The top 10 of the new May 7-dated Billboard 200 chart is scheduled to be revealed on Billboard’s websites on Sunday, April 24.

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A Sailor’s Guide to Earth is Simpson’s debut effort for Atlantic Records, and follows two earlier albums, released through Thirty Tigers. The singer/songwriter's last album, Metamodern Sounds in Country Music, was released in 2014. It debuted and peaked at No. 59 on the Billboard 200 and No. 8 on Top Country Albums, and has sold 192,000 copies in the U.S., according to Nielsen Music. The set garnered a Grammy Award nomination for best Americana album. His first album, High Top Mountain, was released in 2013 and reached No. 11 on the Heatseekers Albums chart the following year (it missed the Billboard 200).

Meanwhile, Rihanna’s Anti could stage a return to the top slot, for a third nonconsecutive week at No. 1. The pop diva's Anti has the edge in SEA and TEA, thanks to the popularity of the songs on the album -- like the reigning Billboard Hot 100 No. 1 single “Work.” Forecasters suggest Anti could sell around 10,000 to 15,000 in traditional album sales for the week, while the rest of its total units will be comprised of SEA and TEA. The math is flipped for Simpson’s album, as the bulk of its units will likely come from pure album sales -- over 40,000.

Elsewhere in the top 10, look for Santana to notch its 14th top 10 album, as Santana IV could start in the region with perhaps 30,000 to 35,000 units.