Justin Bieber is back in the studio and he's reportedly working with Miley Cyrus.

After Cyrus' split with former fiancé, Liam Hemsworth, Selena Gomez is worried Bieber will hook up with Miley Cyrus, and Selena's jealous.

A friend of Selena's told Life and Style Mag that "Justin and Miley hooked up a few years ago. Then he started dating Selena. It created this whole jealously thing between them. Now Selena doesn't want Justin anywhere near Miley - and they've been fighting about it!"

The report came the very same day that Miley and Liam's engagement was broken off; although, there have been disputes to that report.

So what does Selena have to fear?

Well, Bieber and Cyrus will be spending some time together in the studio, as Cyrus first revealed on the red carpet at the 2013 Billboard Music awards.

Both Justin Bieber and Miley Cyrus were spotted at a Los Angeles recording studio on May 16 and she did present him with a Billboard Music Award just a couple days later. Remember, the booing?

But they were only cordial with each other with Justin pecking Miley on the cheek as he accepted the award (the cacophony of boos would come later).

But the two do know each other quite well. They appeared in an episode of Ashton Kutcher's MTV spoof Punk'd! and they're continuing to work together.

In November of 2012, HollywoodLife.com reported that Serena was against the Punk'd idea from the beginning and wanted nothing to do with it.

"Selena is repulsed by Miley!” the source claimed at the time. “Justin did the show anyways, which didn’t sit very well with Selena. He’s been continually choosing work over Selena and she’s finally had enough.”