LONDON – As Britney Spears prepares to launch her seventh studio album "Femme Fatale" on Tuesday, the pop star faces keen competition from Lady Gaga, Katie Perry and Rihanna, who reign atop Billboard's Hot 100 singles ranking.

Singer Britney Spears performs on ABC's "Good Morning America" at Bill Graham Civic Auditorium in San Francisco, California March 27, 2011.[Photo/Agencies]

Her younger rivals' dominance this week may be coincidental -- indeed, Spears also topped the ranking recently with "Hold It Against Me." -- but the chart is a reminder of how crowded the pop diva market has become since Spears rose to fame as a teenager.

There is little doubt her fans will ensure brisk sales -- Spears has sold nearly 70 million albums, according to label Jive Record -- and her music is making headlines again instead of personal meltdowns, a custody battle and rehab stints.

Spears kicked off a string of promotions for the album on Friday with a performance at a Las Vegas nightclub. On Sunday in San Francisco she will record a sold-out mini-concert to be aired on ABC's "Good Morning America" TV show on Tuesday.

Yet after more than 10 years in the music business, Spears, now 29, may have to do more to remain relevant in the era of Gaga, critics say.

"As far as novelty goes, her natural demographic now has an icon as quirky and characterful as Lady Gaga to fascinate and fuss over," said Andy Gill of Britain's Independent newspaper.

"Gaga's music, let's be frank, is not that much better than, or even different to, that on 'Femme Fatale', but she knows the lingering appeal of playing dress up," he added in a two-out-of-five star review of Spears' record.

Adrian Thrills of the Daily Mail added: "The one-time gymslip diva has had to contend with the emergence of Lady Gaga, Katy Perry and Rihanna -- a brash new wave of female performers who have made their mark while seemingly exercising far more creative control."