It was Little Mix's Jade Thirlwall and Pharrell Williams!

This image appears in the gallery:
Summertime Ball 2014 Line-Up: Face Mashup Quiz

1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 

10. 20 images

See the full gallery: Summertime Ball 2014 Line-Up: Face Mashup Quiz