THIS is how you kick off an era! Christina debuted the blaring, funky, DJ Premier-produced "Ain't No Other Man" with this explosive performance at MTV's annual movie awards. The jazzy intro set the tone for the performance and era: When the silhouette of Baby Jane (Christina's BTB alter ego) appeared and belted out that now-famous opening note, it was game on. – Mark Sundstrom, Senior Digital Producer

With "old Hollywood" curls in her hair and a flirty dress (check out that sexy leopard print accent!), Christina looked every bit the ‘30s starlet for her MTV Back to Basics special. She commanded the audience with just a microphone, her passionate vocals and a backing band. When you have the talent, you don’t need distractions. – Bianca Gracie, Associate Writer

This is one of the few times Xtina really went for that big note at the end... and slayed it! The whole Good Morning America show was great and helped kick off the era with a bang. – Jeff Benjamin, Features Editor

I explained why "Hurt" is one of my favorite Christina ballads in our BTB song ranking list, but a performance like this does the explaining for me. "Hurt" is not an easy song to sing, let alone outside, on a cold November night in New York City, but Xtina's seamless transitions between power belts and gorgeous soft falsettos demonstrated her impressive vocal ability. – Mark

Christina so flawlessly pulled off this performance on long-running popular German variety show Wetten, Dass..? that people still argue to this day about whether or not she lipped it. For the record, she didn't. Whew! – Mark

Christina performed "Makes Me Wanna Pray" a few times toward the end of the BTB era and it made me realize how much single potential it had. It's such a feel-good jam and I think with the right radio edit it could have been a breath of fresh air at Top 40. – Jeff

What else is there to say about this legendary GRAMMY performance? The look on Jamie Foxx's face at the end sums it up. After music icon James Brown passed way on Christmas day 2006, the GRAMMYs knew a tribute was in order for the Godfather of Soul. When they asked Christina to be part of it, she knew she had to nail it, and she did. A career-defining moment for Aguilera. – Mark

The MTV Movie Awards debut of "Ain't No Other Man" may be the definitive performance for most fans, but this high-energy, spot-on staging of the hit song gave people a taste of Xtina's Back to Basics Tour opener... lit-up staircase, matching suits and all! – Mark

Xtina has always been open with her fans, and she continued to expose her soul on her Back to Basics tour. “Oh Mother,” one of the singer’s most honest songs to date, is about the domestic abuse she witnessed as a child. This performance brings the chilling lyrics to life, as Christina's heartbreaking emotions read clearly on her face. Her high note at the 3:03 mark takes the performance to another level!
– Bianca

While the original "What a Girl Wants" is damn-near flawless, sometimes a new spin on a classic is welcome. Christina did just that when she gave the 1999 hit a reggae makeover for her Back To Basics Tour in 2007. This performance, taken from Aguilera's Back to Basics: Live and Down Under tour DVD, shows Xtina owning her past and having fun with it. Fun fact: She didn't even perform breakout smash "Genie in a Bottle" on this tour. – Mark