Taylor Swift performs Calvin Harris song live at Grand Prix

Yiiiiiiiiiiiiiikes, this is a tad awkward. 

Taylor Swift performed her ex Calvin Harris' hit song 'This Is What You Came For' at the Grand Pix on Saturday.

Incase you forgot, Taylor actually co-wrote this song for Calvin and Rihanna back when she and Cal were still together.

Watch a snippet of the performance below:

 

We LOVE it, but how did Calvin feel about his ex gf performing his hit song?? According to an exlusive report from HollywoodLife he "absolutely loved it."

The close source went on to reveal that, "regardless of his feelings for her, it is a great song that he is going to play for his own concerts the rest of his life."

"Calvin can't ever get away from it and seeing her performance he thought Taylor knocked it out of the park."

We guess it was bound to happen sooner or later...