"2 Become 1" was originally going to be released in the UK on 9 December 1996, but the release date was delayed to let Dunblane's "Knockin' on Heaven's Door"—a tribute to the children killed at the Dunblane Primary School in Scotland—to stay at the top of the UK Singles Chart. The single was released the next week, debuting at the top, becoming the group's third chart-topper and their first Christmas number-one single in the UK. It sold 209,000 copies in the first three days of release and 462,000 in the first week, becoming the fifth best-selling single of the year. "2 Become 1" sold 1.14 million copies in total, giving the Spice Girls their second and final million-selling single in the UK. Despite being released during the final two weeks of 1996, "2 Become 1" was the 5th best seller of the year and that year's fastest selling single of the year.