British girl group The Spice Girls managed to break the American market, becoming the most commercially successful British group in North America since The Beatles. Their impact brings about a widespread invasion of teen pop acts to the US charts which had been predominantly dominated by grunge and hip hop prior to the success of the group. Between 1997 and 2000 American teen pop singers and groups including Backstreet Boys, *NSYNC, 98 Degrees, Hanson, Christina Aguilera, Britney Spears, Jessica Simpson, Mandy Moore, Jennifer Lopez and Destiny's Child became popular, following the lead of The Spice Girls by targeting early members of Generation Y. At the end of the decade, Britney Spears and Christina Aguilera had huge successes with their hit singles, "...Baby One More Time" and "Genie in a Bottle" and respective debut albums which remain among the best selling of all time. Britney Spears's single/ album went onto the top of the US charts in early 1999. "Womanizer" (Jive) was the second No. 1 hit for Spears after her debut single, " ... Baby One More Time." Spears has the longest gap between No. 1 hits since Cher's "Believe" claimed pole position in March 1999, just 10 days shy of 25 years after "Dark Lady" landed in first place.