Rihanna and Chris Brown recorded their forthcoming duet in secret last year, according to reports.
The Umbrella hitmaker announced this week her new studio album, Unapologetic, will feature a track with her ex-boyfriend, entitled Nobodies Business (sic).
Rihanna and Chris split in 2009 after he was convicted of assaulting her.
The pair fuelled rumours of reconciliation after he split from girlfriend Karrueche Tran last month.
According to HollywoodLife.com, the pair recorded their secret collaboration months before the split.
"They collabed on that track many months ago and both of them wanted to keep that under wraps until the time was right," a source told the website, adding the pair told no one they working working together.
Newly-released lyrics hint the former couple are back on.
"Me and you/ Said ain't no nobody's business,” Chris sings on repeat.
"Your love in perfection/It's point me in the right direction." Rihanna sings, later adding: "I want to be your baby/ You'll always be my baby/ And sing it to the world/Baby give me some/I'm gonna be your girl/And it ain't nobody's business."
Rihanna has previously worked with Chris on tracks including Birthday Cake and Turn Up The Music.
Unapologetic is scheduled for release later this month.