In 2000, NSYNC did one of the most clever marketing moves for their sophomore album, "No Strings Attached". They released the first single, "Bye Bye Bye" months before the album. The song was so hot that the week the album came out, it went flying off the shelves. In fact, the album still holds the record, and it will probably never be broken, with largest number of sales in a single week with 2.4 million. (NSYNC's follow up, "Celebrity" has the second largest, but more on that in 2001).
No Strings Attached was an excellent album, and even though "Bye Bye Bye" is probably not my favorite track today, and probably not even then - it epitomized how NSYNC was going to set itself apart from other boy bands. The definitely pursued a harder dance sound, with better vocals. Justin Timberlake starts to emerge as the one with greater appeal - passing JC Chasez, but the two continue to share the lead vocals - and will do as long as the group remained together - which wasn't that much longer.