Britney Spears and Christina Aguilera's 20-year feud can be traced back to one 2003 interview.

There's a lot that fans expect from Britney Spears' forthcoming memoir, The Woman in Me: plenty of Justin Timberlake goss, several accusations about her family and conservatorship, and of course, a few shady comments sent Christina Aguilera's way.

The two pop stars monopolised mainstream music throughout the early '00s, but they always hated each other. Or so the tabloids would have us believe.

But the reports of a rivalry between Britney and Christina have continued to persist for more than 20 years. In a recent interview with Jimmy Kimmel Live, Aguilera was asked if she thinks she will be mentioned in the memoir. 

"Has she called you and said, 'Hey, heads up?'" asked the host.

"Dude, I don’t know," Aguilera replied. 

"Are you hoping that you’re in it?" Kimmel pressed, to which the 'Fighter' singer replied, "Am I hoping? I mean, I’m hoping that, you know, everything is all good with her and everything’s beautiful. I think the future should be celebrated."

Listen to The Spill hosts talk about the years-long beef between the two women. Post continues below.

Ultimately, it doesn't sound like the singer wants to be in the book, joking with Kimmel that she'd prefer he was in the memoir instead. "I’d rather be it you than me. So hopefully you’ll be in it. You’ll make the book."

Watch the moment here. Post continued after video. 

So how did we get here?

This is Britney and Christina's relationship timeline charting the highs and lows of their friendship.

1993: Britney Spears and Christina Aguilera meet.

Spears and Aguilera first met in 1993 when they were cast on the kids' variety show The Mickey Mouse Club, alongside Justin Timberlake, Ryan Gosling and Keri Russell.

In her upcoming memoir, Spears said that she and Christina were close in those days. "The Mouseketeers quickly split into our own cliques, divided by the dressing rooms that we shared: Christina Aguilera and I were the younger kids, and we shared a dressing room," she wrote in a excerpt shared by People.

Britney looks back fondly on her time on the show. "It was honestly a kid’s dream – unbelievably fun, particularly for a kid like me. But it was also exceptionally hard work: we would run choreography 30 times in a day, trying to get every step perfect."

In 2018, Aguilera also shared she has nothing but love for her years singing and dancing alongside Spears. "The casting agent was a genius back then to get all of us together," she told Entertainment Tonight. 

"It was just such a... special magic in the air."

1999-2000: Britney Spears and Christina Aguilera debut as pop music icons. 

Britney's breakout first single, 'Baby One More Time', was released in January 1999 and would change the look and sound of pop music forever. Just four months later, Christina would make her debut with 'Genie in a Bottle'.

Britney came first and this is important because literally every young and blonde female performer to follow her, including Christina, Pink, Mandy Moore and Jessica Simpson, would be accused of 'trying' to be the next Britney Spears. Throughout the early '00s, each of these women would be pitted against each other in the tabloids.

"When I was coming up, it was very obvious, you know? Me and Britney were definitely [considered rivals]," Aguilera reflected on Jimmy Kimmel Live! in 2018.

In 2000, Britney and Christina presented an award together at the MTV VMAs, suggesting the former childhood pals were still friendly with each other.

Britney Spears and Christina Aguilera at the 2000 MTV Video Music Awards. Image: Getty. 

2003-2004: The feud begins after Britney Spears and Christina Aguilera's 'Like A Virgin' performance. 

Aguilera and Spears performed with Madonna at the 2003 MTV VMAs in an iconic performance of 'Like A Virgin', which culminated in Madonna kissing both women. But you wouldn't know that from watching the live show. Christina's kiss was overshadowed by the cameras cutting to catch Justin Timberlake's reaction to his recent ex Britney's pash.

"It was weird. And you know why they cut away for it? Because they cut away to get Justin [Timberlake]'s reaction," Aguilera reflected during a 2018 Radio Andy interview. 

This was part of the explanation, but the other side to consider was that Christina was in her Stripped album era, which was all about flaunting and owning her sexuality. Britney, meanwhile, was in her Oops!... I Did It Again era, which was an innocent and chaste time for the pop singer, making her kiss with Madonna that much more shocking for viewers.

"I definitely saw the newspaper the next day. It was like, 'Oh, well, I guess I got left out of that one,'" Christina reflected.

This experience must have left a bitter taste in Christina's mouth because she started the feud later that year in a interview with Blender, where she claimed Britney had acted standoffishly with her during rehearsals.

"Every time I tried to start a conversation with her – well, let's just say she seemed nervous the whole time," she said. "She seems to me like a lost little girl, someone who desperately needs guidance."

This moment is where the troubles truly began; when the battle started.

Spears did not take kindly to these comments, sharing a very different version of events. 

"A lost girl? I think it's probably the other way around. I can't believe she said that about me," the 'Sometimes' singer told Blender later that year.

"She comes up to me in a club in front of all these people and tries to put her tongue down my throat!" Britney claimed. 

"I say, 'It's good to see you,' and she goes, 'Well, you're not being real with me.' I was like, 'Well, Christina, what's your definition of real? Going up to girls and kissing them after you haven't seen them for two years?'"

Britney painted a picture of a fractured friendship. "When someone has been rude to you so many times, it's like, 'You know what, Christina, I'm really not about the fake anymore.'"

Aguilera took another swipe at her former friend in 2004, when she told Us Weekly, "I know Britney. She's not trailer trash, but she sure acts that way."

She also took aim at the engagement ring Britney bought after becoming engaged to her backup dancer Kevin Federline. "It looks like she got it at QVC," Christina said, which is a network shopping channel. The shade!

2005-2008: Britney Spears and Christina Aguilera's friendship might be back on track.

The next year, Spears made a gesture to reconnect to Aguilera. 

"Britney would love to be close with Christina again," Spears' official website posted in 2005. "In fact, Britney recently wrote Christina a letter telling her how happy and beautiful Christina looks lately."

Aguilera also shared that in September of that year, she sent Spears presents when she gave birth to her first son, Sean.

In 2008, Christina had nothing but positive sentiments for Britney. "There have been so many stories about the two of us not getting on," she told the Daily Mail.

"It must have seemed as if we were competing with each other, but, in reality, Britney is someone that I used to hold hands with. We were silly little girls together on The Mickey Mouse Club. What a journey it has been for both of us!"

2012: The rivalry is (almost) revived with The X-Factor and The Voice. 

Spears made her reality TV debut on the 2012 season of The X-Factor as a judge, which premiered on a different network at the same time that Aguilera was starring as a coach on The Voice.

At the time, Simon Cowell tried to dredge up the old feud by telling TMZ that Britney wasn't "going to appreciate the fact that Christina – who has been a bit of a rival – isn't allowing Britney to have a night of her own."

But Christina refused to engage in the tabloid fodder.

"We were very close, and our paths have always crossed and, interestingly, they will continue to cross," Aguilera told reporters during a 2012 press conference. "I’m not down with [pitting women against women] at this point of my life... It’s a fun thing to be a part of and I think she’ll have fun with it."

2018: Christina Aguilera suggests doing a duet with Britney Spears. 

During an appearance on Jimmy Kimmel Live! in September 2018, Christina said that she thought her feud with Britney would have ended sooner if the two pop stars had social media. 

"If we had social media back then, we would have probably done a song or something together and squashed it," she said. "Back in the day, when people were comparing me to other artists... I would have loved to be able to squash [any beef] before having an interview."

Christina told the host she would be "down" to do a duet performance with Britney.

2021: Christina Aguilera advocated for Britney Spears during her conservatorship trial. But it was too little, too late for Britney.

At the end of 2021, Britney Spears had her conservatorship trial to decide if it would be terminated after more than a decade. Off the back of the #FreeBritney movement, Christina shared her support.

"These past few days I’ve been thinking about Britney and everything she is going through," Aguilera shared on Twitter in September of that year. 

"It is unacceptable that any woman, or human, wanting to be in control of their own destiny might not be allowed to live life as they wish. To be silenced, ignored, bullied or denied support by those 'close' to you is the most depleting, devastating and demeaning thing imaginable. The harmful mental and emotional damage this can take on a human spirit is nothing to be taken lightly."

She continued, "To a woman who has worked under conditions and pressure unimaginable to most, I promise you she deserves all of the freedom possible to live her happiest life. My heart goes out to Britney. She deserves all the TRUE love and support in the world."

However, Spears suggested Aguilera's statement was hypocritical a couple of months later, in November.

She posted two contrasting videos, one showing Lady Gaga speaking up about Britney in the past and one showing Christina saying she didn't want to comment. "13 years being in a corrupt abusive system yet why is it such a hard topic for people to talk about???” Britney posted in an Instagram Story in November 2021. 

"I’m the one who went through it!!!! All the supporters who spoke up and supported me, thank you … Yes, I do matter!!!!!"

In January 2022, when speaking about Spears' conservatorship being terminated, Aguilera made another effort to rekindle their friendship.

"I would love to [speak to Britney], I would always be open to that," she said on The Enrique Santos Show. "It’s a subject that I definitely want to be careful of because I never want to speak out of turn about somebody that I have so much respect and admiration for. But I’m so happy [for her]."

2022: Christina Aguilera unfollows Britney Spears after she makes body-shaming comments.

Just when it looked like these two might finally lay their feud to rest, Spears made a baffling comment body-shaming Aguilera and her dancers.

In September 2022, Spears shared an image of a tone-deaf, fat-phobic Rodney Dangerfield, with the caption, "I mean if I had Christina Aguilera’s dancers, I would have looked extremely small. I mean why not talk about it??

"Don’t you think my confidence would have been a bit better if I could choose where I lived, ate, whom I called on the phone, dated and who was on stage with me."

The post was met with extreme backlash which led to Spears backtracking. 

"By no means was I being critical of Christina’s beautiful body, it is what it is!!!" Spears wrote. "I flew to see her show once and the main thing I noticed was the difference of our people on stage!!! By no means did I even mention Christina, look at my post!!! I was inspired by her show and she is a beautiful woman of power... Thank you @xtina for inspiring me!!!"

But the damage was done, with Christina promptly unfollowing the fellow star on the social media platform.

Feature image: Getty.