What's even better, he came into training camp after a 4-0 win over Fulham last weekend.
"It's always nice to arrive with the national team after a great victory and a clean sheet," Mignolet said.
With a series of great results, Belgium has shot up the FIFA rankings to fifth place.
Courtois has been Wilmots' choice throughout the qualifying campaign, and kept six clean sheets as they sealed qualification for the finals.
Belgium has a good tradition when it comes to World Cup goalkeepers. Jean-Marie Pfaff was voted the best World Cup keeper in 1986 and Michel Preud'homme took that honor eight years later.
Wilmots said Tuesday that the injury to Courtois was not that serious at first sight. He got a foot trapped in his netting during training late Monday.
"He tweaked a ligament and will take an MRI (scan)," Wilmots said. "Let's wait for the results. But in any case it was not too, too bad."