went on as a half-time substitute in the friendly at Genk's Cristal Stadium, finding the net with a low finish in the 71st minute to stretch his side’s lead.
started the game, our defender being withdrawn with 13 minutes remaining, while Mousa Dembele was on the bench.
The Red Devils also face Sweden and Tunisia before travelling to Brazil with their group opener against Nabil Bentaleb's Algeria in Belo Horizonte on June 17.
"It's a dream to go to the World Cup and makes us all very proud," said Jan.
"My first memory as a young kid is the World Cup of 1994 and now to play there myself, it’s one of the best achievements I'll ever manage.
"Playing in the World Cup is an unbelievable thing for me and it makes me a very proud Belgian."
Elsewhere, Hugo Lloris and France take on Norway in a friendly on Tuesday while Christian Eriksen is back in friendly action for Denmark against Sweden on Wednesday.
Meanwhile, Kenny McEvoy started for Republic of Ireland Under-21s as they drew 1-1 with Qatar Olympic on Saturday.
Our young winger played 60 minutes, before being replaced for the last half-an-hour.