Christina Aguilera just dominated Nashville. The pop diva headed to the show this week as Jude St. John, Jeff's ex-fiancée, and she brought her powerhouse vocals with her. She sings an original song on this week's episode, and she'll debut another one next week, and if you tuned in on Wednesday, you probably already love "The Real Thing." It's available on iTunes now, and you can listen above and watch her performance below. It's the perfect balance between pop and country, and it's catchy as hell.