The sister trio Haim has managed to make its song “Gasoline” even more inflammatory with the edition of a special guest, Taylor Swift, on a remix released late Thursday.

Swifties had been salivating since earlier in the day when the group posted a short video of singer Danielle Haim singing along with the song while promising: “gasoline remix ft ??? out today.” The triple question marks in question were immediately understood to stand in for Swift, since none of the band’s other high-profile collaborators would have stood up to that kind of half-day-long tease in the end. Fulfilling expectations, the new version of the song features Swift taking over lead vocals from Danielle Haim on the second verse and adding fresh harmony lines as a second chorus kicks in.

Haim wrote in a social media message that “since we released (‘Women in Music Pt. III’) in June, Taylor had always told us that ‘Gasoline’ was her favorite. So when we were thinking about ways to reimagine some of the songs from the record, we immediately thought of her. She brought such amazing ideas and new imagery to the song and truly gave it new life. Thank you @taylorswift for adding your incredible voice and spirit to a song that means so much to us.”

The freshened up “Gasoline” is part of a deluxe edition of the Grammy-nominated “Women in Music Pt. III,” which also features Thundercat popping in for a freshened up version of the R&B track “3 AM.”

The “Gasoline” re-do marks the returning of a favor, or reversal of a spotlight, since Haim made a featured appearance on Swift’s “Evermore” album in December. With Haim taking on backing vocals, that number, “No Body No Crime,” was a light-hearted murder ballad that harked back to Swift’s country days and had a main character, Este, named after one of the Haim sisters.

“I’m the fourth Haim sister now, confirmed,” Swift told Entertainment Weekly in December. “We can’t figure out why we hadn’t collaborated sooner. We’ve toured together, played live together, choreographed dances like we’re at summer camp, but it took a song about avenging your friend’s murder to give us the idea to take this step.”

Swift and Haim first hooked up when the superstar invited the sisters to open 17 dates on her “1989” tour in 2015.

One thing Haim and Swift have in common right now besides their back-to-back collabs: they’re competing for an album of the year trophy, to be given out at the Grammys in March.

Besides being up for album of the year for the group’s third release, “Women in Music Pt. III,” Haim also has a nod for the song “The Steps” as best rock performance. (The group was previously nominated for best new artist in 2015.) Swift, meanwhile, has a total of six nominations this year, also including song of the year for “Cardigan.”

Variety profiled Haim when “Women in Music Pt. III” debuted in June. Read it here, or read their reactions to their Grammy nominations here.