This week's Top  20 countdown got a serious shakeup! Three new songs entered the chart and longtime champ Robin Thicke was bumped down from the No. 1 spot!

Katy Perry floats like a butterfly, but stings like a bee. How else could 'Roar' have claimed the top slot in the countdown?

If there's anyone who can claim the No. 1 spot from Katy, it's Selena Gomez. She entered the list this week with 'Slow Down.' Previous champ Robin Thicke also debuted a new song, the Kendrick Lamar collaboration 'Give It 2 U.' Will either of them be able to match the success of Drake? His 'Hold On, We're Going Home' entered the chart in the No. 13 slot.

Check out the full top 20 below!

Top 20 Songs: Week of September 16 - 22, 2013

20. Justin Timberlake, 'Take Back the Night'
19. Selena Gomez, 'Slow Down'
18. Robin Thicke, 'Give It 2 U' Feat. Kendrick Lamar
17. Taylor Swift, 'Everything Has Changed' Feat. Ed Sheeran
16. One Direction, 'Best Song Ever'
15. Justin Timberlake, 'Take Back the Night'
14. Bruno Mars, 'Treasure'
13. Drake, 'Hold On, We're Going Home'
12. Lorde, 'Royals'
11. Miley Cyrus, 'We Can't Stop'
10. Lady Gaga, 'Applause'
9. Maroon 5, 'Love Somebody'
8. Avicii, 'Wake Me Up'
7. Calvin Harris Feat. Ellie Goulding, 'I Need Your Love'
6. Macklemore + Ryan Lewis, 'Same Love'
5. Lana Del Rey, 'Summertime Sadness'
4. Robin Thicke, 'Blurred Lines' Feat. Pharrell
3. Zedd Feat. Foxes, 'Clarity'
2. Capital Cities, 'Safe And Sound'
1. Katy Perry, 'ROAR'

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.