Both singers have suffered personal troubles in the years since, but have marked 2011 as the year for their career comebacks - the Toxic hitmaker is currently celebrating the release of her new album, Femme Fatale, this week (begs28Mar11), while Christina Aguilera is set to launch herself as a reality show judge on new TV talent contest The Voice.

And the Dirrty star has reached out to Britney Spears via Twitter to praise her new project.

In a tweet she writes, "Hey @BritneySpears Congrats on Femme Fatale release! Can't wait to see what you bring in the next video. xo - Xtina."

Britney Spears immediately responded to the kind words, replying, "Thanks @TheRealXtina. Can't wait to watch you on your new show. Hope we get to hear that voice on The Voice. -Brit."

Britney Spears famously lost custody of her two young sons to her ex-husband Kevin Federline in 2008. She was subsequently hospitalised twice in a month and placed under her father's conservatorship.

Meanwhile, Christina Aguilera filed for divorce from her husband Jordan Bratman last year (10) and was arrested for public intoxication earlier this month (Mar11). She also experienced a blow to her professional reputation after a lyrics flub at the Super Bowl in February (11).