Just days after Justin Bieber joined Taylor Swift onstage for a 'Baby' duet during Swift's Speak Now tour, the two were spotted together again, this time co-writing -- according to producer Kuk Harrell who tweeted about it:

Wow!! Got to see @justinbieber & @taylorswift13 write a song together last night!! SMASH!!!! SMASH!!! SMASH!!! Let's do it again Yall!!!"

Justin Bieber re-tweeted Harrell's post, confirming the teentastic collab, and even added another tweet that just plainly read, "#writing." Swift has yet to say anything on the matter, but the cat's out of the box now!

Songwriter and vocal producer Harrell has worked with the likes of some of today's biggest pop, hip-hop and R&B artists -- winning Grammys for his vocal production hand in Beyonce's 'Single Ladies (Put a Ring on It)' and even Rihanna's 2007 smash 'Umbrella.' That's proof enough that this upcoming Swift-Bieber tune will be pretty catchy, if you ask us.

And after a short glimpse of hearing the two duet 'Baby' on stage, we have to say that their voices mesh quite well together. Swift must have liked the extra attention too, since she posted on her Twitter after the show: “Dear amazing LA crowd tonight, God only knows what I’d be without you. You think you’ve heard LOUD screaming in your life. Then @justinbieber comes out and does a surprise song during your show. Woah. Unreal.”

Bieber replied to her tweet, writing, “@taylorswift13 we should do that more often. : ) great show! #muchlove.”
Sounds like he's going to get his wish!