Guardians of the Galaxy Vol. 2 is shaping up to be a real breakthrough role for Baby Groot. Director James Gunn, along with the cast of the anticipated Guardians sequel, debuted a teaser of the film at San Diego Comic-Con on Saturday — and those who were lucky enough to see it can't stop talking about Baby Groot, who really steals the spotlight from Chris Pratt.

But Pratt doesn't really mind. (Although, he may be crying on the inside — it's hard to tell.) "I'm thrilled about it," Pratt told MTV News's Josh Horowitz after the Marvel panel. "In fact, that, to me, was a big test. Anytime in animation you create a character, completely out of nothing, if they can't make you feel something, then that storyline is just not going to work."

"I don't think they're responding simply because he's cute — although, that is one bonus — but he really makes you feel something," Pratt added. "You truly want to protect this wonderful little character."

Baby Groot wasn't the biggest Guardians surprise to come out of Comic-Con. After months of speculation, Gunn confirmed that actor Kurt Russell would in fact be playing Ego, Star-Lord's father in the forthcoming sequel.

"That relationship is so important," Pratt told MTV. "It's the major thread for Quill and his story in this movie. When James first told me about the movie, before Kurt [Russell] was ever a part of it, it just moved me to tears. [Kurt] being cast in it was just an extra amazing element to something that was already so special."

Star-Lord's daddy issues might be the film's emotional center, but all of the Guardians are going through major emotional arcs in this one. "The first movie was about becoming a family, and this one's about being a family — and being a family is a lot harder," Gunn told MTV.

For example, Rocket Raccoon really went through it in the first film — losing Groot and finding him again — but Guardians Vol. 2 will test Rocket even further. "No one's ever given that guy any sort of love, and he's not comfortable with it," Gunn said.

"It's a better screenplay this time around simply because everybody works together so well this time around," he added. "It's a family drama, but it's also an action film."

Guardians of the Galaxy Vol. 2 hits theaters May 5, 2017.