Scoring its second No. 1 with "Mezmerize," System Of A Down leads an influx of Billboard 200 entries, breathing life into the chart after weeks of declining sales. The American/Columbia title provided

Scoring its second No. 1 with "Mezmerize," System Of A Down leads an influx of Billboard 200 entries, breathing life into the chart after weeks of declining sales. The American/Columbia title provided the rock act with a career-best sales week, moving 453,000 copies in the United States, according to Nielsen SoundScan.

The set is the first half of a double album released as two separate discs, with follow-up "Hypnotize" expected in November. System of A Down previously reached the summit with 2001's "Toxicity," which has sold 3.5 million to date.

"Mezmerize" is one of five top 10 debuts (and nine in the top 20) of The Billboard 200, reflecting a week when overall U.S. album sales were up 4% over the previous week, and 3% over the same week last year.

At No. 2, Toby Keith's "Honkytonk University" opens with 283,000 copies, falling short of previous pole position debuts by the DreamWorks Nashville artist. In 2002, "Unleashed" started on top with 338,000, while 2003's "Shock'N Y'All" began with 585,000. Together, the albums have sold 8.3 million.

Kem's sophomore Motown effort, "Album II," moved 140,000 copies to give the R&B artist his best sales week and his highest chart position with a No. 5 entry. His 2003 debut, "Kemistry," opened at No. 175 with 6,000 and has gone on to sell 601,000.

In anticipation of this week's season four "American Idol" finale, fans clamored for "American Idol Season 4: The Showstoppers" (RCA), which sold 83,000 to open at No. 6. The debut is better than "American Idol Season 3: Greatest Soul Classics," which started at No. 10 with 55,000; it has sold 262,000 to date.

With a double-disc compilation, veteran rock act Def Leppard makes a return to the top-10 of The Billboard 200, its first appearance there in a dozen years. "Rock of Ages: The Definite Collection" (Mercury) bows at No. 10 on the strength of 66,000 copies sold. The group last reached the top tier in 1993 with the rarities compilation "Retro Active," which peaked at No. 9.

Rounding out the top-10, Mariah Carey's "The Emancipation of Mimi" (Island/Def Jam) holds at No. 3 for a second week on a 0.2% increase to 173,000, while last week's No. 1, Dave Matthews Band's "Stand Up" (RCA), slides to No. 4 on a 66% drop to 158,000 copies.

50 Cent's "The Massacre" (Shady/Aftermath/Interscope) falls 4-7 on a 9% dip to 81,000; Gwen Stefani's "Love, Angel, Music, Baby" (Interscope) drops 7-8 despite an 8% gain to 80,000; and Weezer's "Make Believe" (Geffen) slips 2-9 on a 61% slide to 76,000.

Landing inside the top 20, Memphis Bleek's "534" (Roc-A-Fella) arrives at No. 11 on career-best sales week of 60,000, followed by Big & Rich collaborator Cowboy Troy's debut, "Loco Motive" (Warner Bros., No. 15, 51,200), fellow newcomer Natalie's self-titled bow (Universal, No. 16, 51,000); and Rhino's "Totally Hits 2005" (No. 20, 44,000).

Rounding out the top 100 debuts are Van Morrison's "Magic Time" (Geffen, No. 25) and the Insane Clown Posse EP "The Calm" (Psycopathic, No. 32).

At 218 million units, overall U.S. album sales for 2005 remain behind those of last year by about 8.5%.