Sum 41's Deryck Whibley (Sun file photo)

They may be underclass, but Sum 41 are heroes in the eyes of a few Canadians.

The Ajax, Ont. band's fifth studio album, "Underclass Hero," topped the Canadian album charts this week on unremarkable sales of just over 9,000 copies, Nielsen SoundScan reports.

The album, the first without long-time guitarist Dave Baksh, marks the first time the punk-pop trio had hit No. 1 here. Their last album, 2004's "Chuck," fell just short, coming in at No. 2.

South of the border, "Underclass Hero" debuted at No. 7, selling 45,000 copies in the U.S.

Back in Canada, Rihanna's "Good Girl Gone Bad" remained at No. 2, Bon Jovi's "Lost Highway" moved from No. 1 to No. 3, and Tegan & Sara had the best debut of the week, and the best ever chart placement at No. 4 with "The Con."

One of the biggest moves of the week went to the "Hairspray" soundtrack, which jumped 11 positions to No. 5, while Timbaland's "Timbaland Presents: Shock Value" slipped one spot to No. 6.

Michael Buble's "Call Me Irresponsible" claimed the No. 7 slot, Claude Dubois' "Duos Dubois" sank from No. 3 to No. 8, Fergie's "Duchess" moved down two to No. 9, and Avril Lavigne's "The Best Damn Thing" hung on at No. 10.

Notable debuts this week belonged to Prince's "Planet Earth" at No. 14, Silverchair's "Young Modern" at No. 25, and the Yeah Yeah Yeahs' "Is Is" at No. 44.

Back in the U.S., "NOW 25" stayed at No. 1, followed by the "Hairspray" soundtrack" in second, Prince in third, the "Hannah Montana 2/Meet Miley Cyrus" in fourth, and T.I.'s "T.I. vs. T.I.P." in fifth.