First-half goals from Kevin Bruyne and Michy Batshuayi were enough to seal the victory for Belgium in the Stade Roi Baudouin.
KDB gave the lead in the 11th minute, receiving the pass from Batshuayi before hitting a 20-yard strike past Wayne Hennessey.
The roles changed in the 37th minute, this time De Bruyne set up Michy to score the team’s second of the night.
De Bruyne almost got his second and a third, but Hennessy did well to deny the Manchester City man.
Early In the second half, Bournemouth striker Kieffer Moore pulled one back for Wales, standing up to a cross by Brennan Johnson before nodding past Courtois.
Chances fell to the path of Belgium to restore their 2-goal lead, but they couldn’t convert any.
However, they held on to their slim lead to ensure they stay in the race to the top spot of the group.