f(x) performed a surprise stage for their "triple crown" victory.

f(x) on July 13 performed on Mnet "M! Countdown" with their debut song, "La Cha Ta." Last week, they won 1st place three weeks in a row with their title song, "Electric Shock." In order to celebrate their "triple crown" victory, they performed this special stage.

Unfortunately, Sulli was not able to perform on this stage due to her filming schedule for her new drama, "To the Beautiful You."

Fans were disappointed that Sulli did not appear for the encore song of  "Electric Shock" either.

Sulli will be playing a role in the new drama, "To the Beautiful You," which is about a gold medalist who has suffered from an injury. It will air in August.