After a stint as Winnipeg's biggest garage rock heroes in the mid-'60s, The Guess Who brought on board a new lead singer, Burton Cummings, and changed their sound. Adopting a softer feel akin to The Zombies, the group scored international hits with ballads like "These Eyes" and "Undun." Reintroducing hard rock into the mix via Randy Bachman's heavy guitar, 1970's "American Woman" became the first U.S. No. 1 single by a Canadian act. Even after Bachman split to form Bachman-Turner Overdrive, The Guess Who scored hit singles like "Clap for the Wolfman" into the mid-'70s.