The South Korean forward scored the only goal on Tuesday night as Spurs defeated CSKA Moscow 1-0 at Arena CSKA in the Champions League.
The goal was Son's fifth in his past five outings in all competitions and his form has been lauded by Pochettino who has highlighted the importance of filling the void for the injured Harry Kane.
"I think it is key," Pochettino said of Son's form.
"It is very important that not only Harry, who was good before his injury and scored, that now another player has scored and that is very important for the team.
"I feel very pleased for Sonny. He is on fire and to keep this form is very important for us."