Smith being involved in training was one of the surprises from the club's training session on Tuesday.
It is the second time that Smith got to train with first team stars, as he was involved in Mikel Arteta's very first session back in December.
He has impressed in his games with the under-23 team this season.
Arteta wants him to train with the club's best players so he can run the rule over him.
The Spanish coach wants to determine if the youngster can play with the first team next season, or may benefit from a loan move.