Milinkovic-Savic is one of the most sought after talents in Europe, whose stock will only rise if he delivers in Russia.
The Lazio man has been linked with many of Europe's top clubs, including Manchester United and Juventus, after playing a pivotal role in the Italian side's qualification for the Europa League.
Despite having only four caps to his name, the 23-year-old looks set to start in a midfield three with experienced pair Nemanja Matic and Luka Milivojevic in the Group E clash in Samara.
Costa Rica boast one of the most miserly defences coming into the World Cup, conceding just eight goals in 10 qualification matches.
Their defensive organisation and resilience was also behind their historic run to the quarter-finals in 2014 and coach Oscar Ramirez will once again be looking to build from the back in Russia.
Milinkovic-Savic, who scored 12 goals in Serie A last season for Lazio, will likely play behind Aleksandar Mitrovic on Sunday but Krstajic refused to put extra pressure on the pair.
"They are they are young, up and coming ambition players, who are proving themselves," Krstajic told reporters.
"I do not see inordinate pressure on them, even through many people want to (put pressure on them) but they know what to do and are fully focused."
HIGHLY RATED
Despite being highly rated after helping Serbia to win the under-20s World Cup in 2015, Milinkovic-Savic only has four caps due to failing to impress former coach Slavoljub Muslin, who lost his job partly because he didn't make the most of the midfielder.
"Milinkovic-Savic was at odds with Muslin before the match against Israel in 2016, when he came into the manager's office to ask why he hadn't been picked," explained Serbian journalist Milos Markovic.
"Muslin claimed Milinkovic-Savic didn't fit in his system but my personal view is that he couldn't find a mechanism to cope with a temperamental young player."
Since Krstajic took over in October, Milinkovic-Savic has featured three times, including the most recent friendlies against Chile and Bolivia.
Milinkovic-Savic, who is nicknamed 'the Sergeant' for his dominating displays, combines a powerful, all-action style with lethal technique.
"The fans can't wait to see him in action," stressed Markovic.
"There is a universal opinion that he could be our 'wow factor' and a difference maker."
All eyes will be on Milinkovic-Savic on Sunday as he looks to give Serbia the perfect start to their World Cup campaign and perhaps adding several more million onto his transfer fee in the close season.
(Reporting by Jack Tarrant; Editing by Christian Radnedge)
