Actor Terry Notary has confirmed that he provided Teen Groot's motion capture performance in Avengers: Infinity War. Notary is known for portraying Rocket in the current Planet of the Apes franchise.
"Yes, I am playing teenage Groot. I’m having a blast with it," Notary told Yahoo! Movies UK. "It’s really, really fun. I can’t say too much about him, but he’s coming of age, so you’ll see the teenager find a mentor to look up to and to model himself after. The character’s great, and the films are going to be great. We’ve got such an amazing cast and a great pair of directors at the helm. The Russos allow the actors to jam on scenes together to the point where it just feels great and everybody gets their moments."
Notary teased another role in the film back in March, portraying a character he called "[Thanos'] right hand bad guy." He is listed as portraying Cul Obsidian of the Black Order on IMDB. Vin Diesel is also listed as providing Groot's voice once again. It is unknown if Groot will play a role in the still untitled Avengers 4.
Avengers: Infinity War is due out in theaters May 4, 2018.