Adele's "21" heads back to the top slot (2-1) on the Billboard 200 for a third nonconsecutive week, selling 98,000 (down 26%), according to Nielsen SoundScan. She bumps last week's champ, Lupe Fiasco's "Lasers," to No. 3 (47,000, down 77%).Debuting at No. 2 is rock band Rise Against with its sixth studio album, "Endgame," shifting 85,000. It easily marks the act's best sales week and chart high. The set surpasses the band's previous record frame, when its last set, 2008's "Appeal to Reason," debuted and peaked at No. 3 off a 65,000 start.

celtic rhythms: Just outside the top 10 on the Billboard 200, Celtic Thunder's "Heritage" takes a St. Patrick's Day-propelled 82-position leap to No. 11 (26,000, up 356%). It gives the ensemble its highest-charting album and best sales frame.On the World Albums chart, all but three of the titles on the 15-position tally post a gain this week. "Heritage" is found, naturally, at No. 1, while the act also takes No. 6 with "It's Entertainment!" (up 67%). The similarly named act Celtic Woman occupies two spots as well, at Nos. 3 and 4, both up by more than 40%.

Celtic rock act Flogging Molly also makes the most of the St. Patty's holiday, as its "Swagger" and "Drunken Lullabies" re-enter the Billboard 200 at Nos. 128 and 171, respectively, with gains of 415% and 90%. The former got a boost from discount pricing at Amazon's MP3 store.

'Born' to stay: Lady Gaga's "Born This Way" remains at No. 1 on the Billboard Hot 100 for a sixth straight week-its entire chart run-thanks to an unlikely culprit: the release of a physical CD single.A four-track single dropped last week, and with 24,000 sold-and a No. 1 bow on Hot Singles Sales-it helps the song earn enough overall Hot 100 points to edge out Katy Perry's surging "E.T." (featuring Kanye West), which bullets 3-2. The latter sold 261,000 downloads (up 21%) and holds at No. 1 on Hot Digital Songs.On the Hot 100, the two songs are separated by 325 points-the smallest margin between Nos. 1 and 2 since the Nov. 27, 2010, tally, when 284 points kept Rihanna's "Only Girl (In the World)" from toppling Far*East Movement's "Like a G6" (featuring Cataracs and Dev). Rihanna's song hit No. 1 the following week-a feat that Perry herself might achieve next issue.

back in black: The Social 50 chart welcomes its highest debut yet, as Rebecca Black arrives at No. 9 thanks to the enormous social media buzz she's generated.In short order, her much-maligned "Friday" video, uploaded to YouTube, went from more than 2 million views on March 14 (already a feat in itself) to 30 million-plus on March 21. Couple that with more than 30,000 new followers to her just-launched Twitter account during the March 18-20 weekend and you've got enough sizzling social activity to generate her top 10 entry.

Her "Friday" single arrives at No. 57 on Digital Songs with 37,000 sold, according to Nielsen SoundScan, and also debuts at No. 72 on the Billboard Hot 100.Black isn't the first so-called Internet meme to make the charts recently. Less than a year ago, on Aug. 28, 2010, Antoine Dodson hit No. 89 on the Hot 100 with "Bed Intruder Song" thanks to a remix by the Gregory Brothers.

the 'F.a.m.e.' game: Chris Brown might be celebrating his first No. 1 album on the Billboard 200 next week, as fourth set "F.A.M.E." is on course to bow with more than 250,000 sold in its first week.

Industry prognosticators suggest the set could shift between 250,000 and 300,000. Brown has charted three previous top 10 albums: His self-titled debut set bowed and peaked at No. 2 in 2005 and was followed by 2007's "Exclusive" (No. 4) and 2009's "Graffiti" (No. 7).

And it's looking like Brown will lead a packed top five, with three more debuts-from Jennifer Hudson, the Strokes and Kirk Franklin-aiming for Nos. 2 and 3.