The 25-year-old, who has one senior cap to his name, played a major role in his club's third-place finish in the Scottish Premier League and their Scottish Cup triumph, and has been rewarded with a place in his country's final squad.
He will travel to South Africa as deputy to number one Jan Mucha, but United old boy Hamish McAlpine is confident he will be ready to step into the breach if required.
He told the Press and Journal: "I really like the look of big Dusan.
"He has all the attributes to be a success, and what bigger stage than the World Cup to prove he has what it takes?
"It doesn't matter he's going there as back-up. No-one knows what's round the corner."