Defender Jan Vertonghen struck in the 78th minute to hand 10-man Belgium a 1-0 triumph over South Korea on Thursday in Curitiba.
Belgium's third straight win at the World Cup clinched top spot in Group H for the Red Devils and set up a meeting with the United States in the round of 16.
Belgium lost Steven Defour to a red card in the 44th minute after the Porto midfielder's reckless tackle on Kim Shin-Wook.
Wilmots made a double substitution soon after with Nacer Chadli and Divock Origi entering the pitch.
Origi wasted little time in helping Belgium take the lead.
His right-footed shot from 20 yards was kept out by Kim Seung-Gyu but the keeper could not hold onto the ball and Vertonghen was on hand to smash the ball into the back of the net.
Despite the numerical disadvantage, Belgium held on for the win.
