It’s Monday night in Southeast D.C., and you can hear the music halfway down the block. It’s a raucous yet cohesive sound—-a mixture of rock-n-roll and R&B, dashed with a little hip-hop and funk.

Step inside the single-family home, and the source of the noise becomes clear: Black Alley is in the midst of a two-hour rehearsal, finalizing the songs they will perform live in the NBC Washington studios this week: “Artist’s Prayer” and “Bad Girl.”

The practice space is artistic enough—-a pile of CDs sit on a dusty flat surface, and the brown-paneled walls celebrate musical pioneers: Aretha Franklin, Eddie Kendricks, and Quincy Jones, among others. A white dry-erase board outlines the band’s immediate plans. There’s the setlist for an upcoming gig and the working tracklist for the group’s upcoming album, Soul Swagger Rock Sneakers, which doesn’t have a release date (Kacey Williams, the band’s vocalist, says the album is definitely in its finishing stages).

In tall green letters, that same erase board brings to light what is arguably Black Alley’s biggest gig ever: “MERRIWEATHER POST PAVILION!!!”

This Saturday, the seven-piece band will open this year’s HFStival at the pavilion, a daylong concert featuring 20 acts, including Diane Birch, Gin Blossoms, and Minus the Bear. Black Alley earned the opportunity to perform this weekend after winning the California Tortilla Battle to Break Out competition at the 9:30 Club last month. (Just for perspective, Good Charlotte once won the Break Out competition.)

During this week’s rehearsal, the band runs through a series of high-energy tracks. “Virgin Suicide,” with a seductive poem at the song’s onset, is methodical until it builds into a full-scale rock track. The aforementioned “Bad Girl” is hard and aggressive, a seemingly perfect song for this weekend’s performance. Then there’s “Used,” a song for anyone who’s been cheated on and lied to, Kacey says.

Still, when Black Alley opens the festival, they are likely to see a different crowd than they are used to playing. They recently performed for Chuck Brown‘s 75th birthday and work every Friday as the in-house band at the Indulj jazz club. With the HFStival, however, the other bands vacillate between breezy alt-rock and punk, and Black Alley’s music is rooted in soul.

“We’re different from what the festival is used to,” Kacey says. “But we don’t fit into any type of box. It will be something new and I think people will be blown away.”

The band plans to end Saturday’s show with a rendition of Nirvana‘s “Smells Like Teen Spirit.” Look out for Animal‘s drum solo. And the possible encore. Word to Nicki Minaj.

Merriweather Post Pavilion is located at 10475 Little Patuxent Parkway, Columbia, MD. Doors at 10 a.m. Tickets are $35-$50.