Song Joong Ki, Jo In Sung and Im Joo Hwan will surprise the 'Running Man' cast with their appearance on next week's episode.

A preview for next week's episode was shown after the episode on June 7th featuring Big Bang ended. For this episode, Haha's wife Byul as well as real life couple Kim So Hyun - Son Joon Ho will appear as guests and compete for the couple race.

In particular, Song Joong Ki, Jo In Sung and Im Joo Hwan are also seen making their special appearance in the preview. Since they won't be there as guests, it seems they decided to visit 'Running Man' in order to cheer on their close friend Lee Kwang Soo.

Check out the preview video