OFFICIAL: Vin Diesel is GROOT in GUARDIANS OF THE GALAXY

Vin Diesel has just posted this on his Facebook page seemingly confirming that he will do the motion capture for the film which will be released next August. Officially announced at Marvel.com

"Vin Diesel is a super awesome dude. I can't tell you how much I like this guy." “I hope this puts to rest all the silly Thanos-Vin stuff which people just seemed to make up out of nothing.” “He said he wanted to do it and we said we were talking to him. Everything else was people guessing and thinking they knew what was going to happen” 

Gunn also talked about the bust of Groot that Diesel is posing next to.

“This was the bust we used for reference when shooting. It has changed slightly from this since we started animating him.”