Why 'Celebrity Treasure Island' co-star punched Sam Wallace in the face

Sam Wallace has been "punched right in the face" by his Celebrity Treasure Island co-star.

It seems things must have gotten tense on the island during filming because former-All Black star Zac Guildford decided to jump in the ring with Sammy and managed to pop him right in the kisser.

Thankfully it was just a friendly match, but Sam claimed he managed to get Zac back too ... although his reach may not have been quite up to the task …

Watch the video for yourself:

Celebrity Treasure Island hits TVNZ 2 on August 18.