Complex sentence: In Europe, "Who's That Chick?" debuted at number nine on the singles chart in the Wallonia region of Belgium on 12 December 2010 and peaked at number on the singles chart in its seventh week on 15 January 2011.
Split into simpler sentences: In Europe, "Who's That Chick?" debuted at number nine on the singles chart in the Wallonia region of Belgium on 12 December 2010. It peaked at number on the singles chart in its seventh week on 15 January 2011.