Jan Vertonghen's finish was the only goal of a cagey game in Sao Paulo, which saw Steven Defour dismissed before half time, but Wilmots believes that the introduction of both Nacer Chadli and Divock Origi was crucial to the outcome.
He told reporters: "You saw again today that the bench is very strong. Everyone who comes in gives 100% for Belgium and that's the nicest thing about today. There's also the victory of course but the manner in which we fought, the winning mentality. I think it's deserved.
"We made the right changes at the right time with the pace of [Nacer] Chadli and [Divock] Origi.
"We played with two lines of four and one up front. Of course, they had to come at us and then they left spaces, which we took full advantage of."
Belgium, now unbeaten in nine consecutive World Cup group-stage matches, will face the USA for a place in the last eight.