The Japan striker impressed in their Capital One Cup win over Bristol City.
Barely used last term, he was farmed out to FC Tokyo on loan for the second half of the season and told he had no future at St Mary's upon his return.
However, Pochettino had a change of heart after being impressed by Lee's attitude and aptitude, leading to his return to the side last night.
"He played very well," No2 Jesus Perez said. "We were talking on the bench about his performance, especially in the first half.
"He was very dynamic, he played not only as a forward but also tried to help team link up and build between the lines.
"I am really, really happy with his performance. It is good news."