Faumuina, 25, has been consistently good for the Blues this season and deserved his first call-up to the national squad. With him on one side of the scrum and Tony Woodcock on the other, the Blues' set piece has rarely gone backwards.
He hasn't injured his calf before and said it felt like a kick to his lower leg when he tried to stand up after a scrum. "But I couldn't stand on it so off the field I went. It's unfortunate for me I guess."
For coach Pat Lam it was yet another kick to the solar plexus.
"It's a massive, massive blow for us and obviously for Charlie," Lam said. "I'm really pleased the All Blacks' selectors have obviously still recognised him. He will still go to those camps and do a lot of learning and so forth but he should be here and bounce back some time in June.
"It's a fantastic reward for where he has come from and the work that he has done. As a team, everyone's pretty happy for him."
While some in Lam's squad could count themselves lucky to be called into Hansen's squad given their form - such as Piri Weepu, Ma'a Nonu and Ali Williams - others were unlucky to miss out, most notably Luke Braid.
Flanker Braid has often been excellent and has had the added weight of the captaincy on his shoulders.
But Lam said he thought the All Blacks squad was a fair representation of the current talent in New Zealand rugby and was reluctant to point out anyone in his squad as unlucky to miss out.
"The way we're going and on form, we can't complain. I think it's a good reflection on reputation, the guys who've done the business for them in the past, and the guys who are coming through."
Fresh from their second win of the season, the Blues play the Crusaders in Christchurch on Saturday and are expecting to face a side still hurting from their shock loss to the Rebels.
"I know they'll be hurting from that and for us, it was a great relief to get that [second win] off our backs and now we can go down there and I imagine it will be a real dogfight."
Asked if he was expecting a forthright response from the Crusaders, Lam said: "Without a doubt. That's what the Crusaders are about and it makes it a bigger challenge for us."