By now it’s probably safe to say that Britney Spears’ pop-princess reputation is almost entirely restored after her latest album, “Circus,” exceeded all expectations, selling over 500,000 records in its first week and prompting Britney among the top five female acts with the most No. 1 album debuts in history.

According to the singer’s label, Britney’s sixth studio album debuted on the #1 spot in U.S. charts as well as five more other countries, including Canada, Brazil and Japan. The huge sales figures prompted promoters of her upcoming world tour, which kicks off in March next year, to add more dates. More than 400,000 concert tickets have been sold in the U.S. so far. The newly added dates include

Although “Circus” marks the second biggest album debut of the year for a female artist, the record  is the sixth biggest opening of 2008, behind albums like Lil Wayne's “Tha Carter III,” AC/DC's “Black Ice,” Coldplay's “Viva la Vida,” Taylor Swift's “Fearless” and T.I.'s “Paper Trail.”

Things have been looking up again for the artist who not that long ago was making headlines with her erratic behavior and personal life. Lately, most reports about Britney Spears have been focusing on her professional achievements and struggle to reinvent herself as a musician.

“Professionally, she's feeling great,” Britney’s manager, Larry Rudolph, told The Associated Press. “It's great for her to hear that she's got a No. 1 album again.”

Unlike her previous “comeback” album, “Blackout,” which barely sold 290,000 copies and quickly dropped from the charts despite its #1 debut, “Circus’” success is also due to the singer’s high-profile performances on ABC’s “Good Morning America” on her 27th birthday and at the Bambi Awards in Germany, where she performed for the first time since her disappointing MTV Video Music Awards in 2007.

Speaking about “Circus,” the singer called it “a little lighter” than “Blackout,” which contained a lot of songs that reflected the difficult period Britney went through last year.

“They're two totally different vibes,” she said. “This one has a lighter feel, a little bit more pop. Blackout is darker, edgier, more urban.” The album’s first single “Womanizer” was a hit while her second single “Circus” is the most added song in pop radio.

Previously, her second, third and fourth albums all racked up half-million weeks: 2000's “Oops! I Did It Again” started with 1.3 million, 2001's “Britney" debuted with 746,000 and 2003's “In the Zone” entered the chart with 609,000.

“Imagine a year ago—did anyone think that today she would be able to come out with an album that would not only just debut at No. 1 but also do half a million copies in its first week?” Billboard Senior Chart Manager Keith Caulfield asked. “It's surprising, but at the same time it's got to be pretty satisfying for Britney and for her record label.”

Britney Spears has come a long way in both her personal and professional life since the beginning of 2008 when her father, Jamie Spears, was named the conservator of her estate after she was hospitalized in a psychiatric ward following two public meltdowns, and loss of custody of her two sons, Sean Preston and Jayden James.

She recently opened up about her new life in a tell-all documentary called “Britney Spears: For the Record” which aired on MTV on November 30.