A megastar's new single makes a top 20 debut, while another star falls behind and a godly gal moves up the chart! It's the top 20 songs of September 9-15, 2013.

Taylor Swift and her BFF Ed Sheeran make their top 20 debut with their duet, 'Everything Has Changed,' landing at No. 20 this week.

Pop newcomer Lorde, who debuted at No. 20 last week, moves up to No. 16 with her surprise smash 'Royals.' Meanwhile, Lady Gaga slides back one slot from No. 15 to No. 16 with 'Applause,' her lead single from 'ARTPOP.'

Gaga's fan-created rival, Katy Perry, jumps from No. 10 to No. 5 this week on the strength of 'ROAR,' whose video debuted last week. In a sign of an unfair world, Sara Bareilles' 'Brave' still isn't on the top 20 chart, but considering how close the production is on these two tracks, it may as well be.

One thing that's not surprising? Robin Thicke's 'Blurred Lines,' which may as well be officially declared the
song of summer 2013, remains firmly perched on the top spot. Check out the full top 20 below!

Top 20 Songs: Week of September 8 - 15, 2013

20. Taylor Swift Feat. Ed Sheeran, 'Everything Has Changed'
19. Paramore, 'Still Into You'
18. Daft Punk, 'Get Lucky'
17. One Direction, 'Best Song Ever'
16. Lorde, 'Royals'
15. Justin Timberlake, 'Take Back the Night'
14. Lady Gaga, 'Applause'
13. Bruno Mars, 'Treasure'
12. Anna Kendrick, 'Cups'
11. Avicii, 'Wake Me Up'
10. Imagine Dragons, 'Radioactive'
9. Miley Cyrus, 'We Can't Stop'
8. Calvin Harris Feat. Ellie Goulding, 'I Need Your Love'
7. Lana Del Rey, 'Summertime Sadness'
6. Macklemore + Ryan Lewis, 'Same Love'
5. Katy Perry, 'ROAR'
4. Capital Cities, 'Safe And Sound'
3. Maroon 5, 'Love Somebody'
2. Zedd Feat. Foxes, 'Clarity'
1. Robin Thicke Feat. Pharrell and T.I., 'Blurred Lines'

Note: Every Monday, PopCrush will publish a list of our Top 20 songs for that given week. Then, over the weekend, fans can tune in to our national radio show to hear all of these hot songs plus some other amazing pop tunes. To see a list of radio stations where you can hear the PopCrush Top 20 countdown, click here.