Her second album The Comfort Zone became the biggest success in her music career. The lead single "Running Back to You" reached top twenty on the Hot 100, and the top position of Hot R&B/Hip-Hop Songs chart on October 5, 1991. Other singles included "The Comfort Zone" (#2 R&B), "Just for Tonight" (#26 Pop), a cover of The Isley Brothers' "Work to Do" (#3 R&B), and the club-only hit "Freedom Dance (Get Free!)." The most successful single from the album, as well as her biggest hit to date, is "Save the Best for Last". It reached No. 1 in the United States, where it remained for five weeks, as well as No. 1 in Australia, the Netherlands, and Canada, and was in the top 5 in Japan, Ireland and the United Kingdom. The album sold 2.2 million copies in the U.S. at its time of release and has since been certified triple platinum in the United States by the RIAA, gold in Canada by the CRIA, and platinum in the United Kingdom by the BPI. The Comfort Zone earned Williams five Grammy Award nominations.