Trésor began his professional football career at the Belgian club Royal Excel Mouscron in 2016. He spent two seasons with the club, making over 60 appearances and scoring 10 goals. His performances caught the eye of scouts from larger clubs, and in 2018, he made a move to Standard Liège in the Belgian Pro League. Trésor continued to impress with his skill and speed, netting 7 goals in 39 appearances for the club.