coup de main - noun
\ˌkü-də-ˈmaⁿ
Definition of coup de main : an attack that achieves complete surprise.

Watch: Florence Welch perform 'Wild Horses' live with The Rolling Stones.

Florence + The Machine opened for The Rolling Stones in London this week, and the band's Florence Welch joined them onstage to perform 'Wild Horses' together live.

Watch the performance below...