At FORM 2018, SOPHIE premiered a new collaboration featuring Petras' vocals. The song was known as “We Don’t Stop” prior to it being confirmed as “1, 2, 3 DAYZ UP” on SOPHIE’s CDJ setlist.

Before the track’s live premiere, Petras spoke on working with SOPHIE in an interview with Huffpost:

I’ve started to collaborate with SOPHIE — I’m such a huge fan.

Live footage of the track can be seen here:

1, 2, 3 DAYZ UP is one of at least two collaborations between Petras & SOPHIE, along with “Reason Why”.