This is the Top Five Countdown where we look at the five most popular songs in the pop singles chart, for the week ending September 21, 2013.

Two of our top five titles change this week - that’s a 40 percent turnover! It all starts in fifth place, where Avicii jumps two slots with The song comes with a pedigree. Released in June, it’s already gone to number one in more than 25 countries, from Bulgaria to New Zealand. It’s a million-seller in the United States, and has topped two separate dance charts.

Top 5 Songs for Week Ending Sept. 21

Also on the rise are Jay Z and Justin Timberlake, as jumps a slot to fourth place. The second volume of Justin’s album hits the market on September 30.

Top 5 Songs for Week Ending Sept. 21

Up a big five slots to third place is Lorde with This young singer may be the year’s fastest-rising star. Just a few months ago, the 16-year-old singer was virtually unknown outside her native New Zealand. Now, thanks to the web, her videos and songs have made her a fast-rising global star, and her debut album is set for a September 30 release.

Top 5 Songs for Week Ending Sept. 21

Holding fast in second place are Robin Thicke, T.I. and Pharrell with It’s a tribute to the song's popularity that the former 12-week champ remains strong in second place. Robin Thicke, T.I. and Pharrell have gone seven times platinum in Australia, six times platinum in Canada, and five times platinum in the United States - meaning this song has sold five million downloads.

Still at number one is Katy Perry with She holds thesingles title for a second week. Katy’s real name is Katherine Hudson - and she sang Christian rock when she released her debut album in 2001. Seven years later she re-emerged as the singer we know and love today.

That’s it for now; join us in one week for an all-new hit list.