Having qualified for Russia top of their group, eight years after they last reached a major tournament, Serbia wasted little time in dismissing boss Slavoljub Muslin, amid grumblings about his team selections and tactics.
In came Mladen Krstajic, a former Serbia defender, who had been Muslin's assistant but had no managerial experience whatsoever.
It was a gamble that could have backfired spectacularly, with Krstajic's first competitive game coming in the Samara Arena against a Costa Rica side with World Cup pedigree after their run to the quarter-finals four years ago.
Yet Serbia were deserved winners and Krstajic clearly came out on top in the tactical battle against his opposite number Oscar Ramirez.
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While it took a moment of brilliance from Serbia captain Aleksandar Kolarov to decide the Group E match, with his curling free kick lighting up an otherwise tight encounter, it was undoubtedly a fair result.
Serbia bossed the ball in midfield, created the better chances and were far more adventurous than the Costa Ricans.
And there were personal victories for Krstajic too.
The team looked much tighter and more composed than under his predecessor, while playmaker Sergej Milinkovic-Savic, who was cold-shouldered by Muslin and played no part in qualifying, also justified his inclusion with an excellent all-round performance.
As did Nikola Milenkovic, Serbia's 20-year-old centre back, who has been thrust into the team by Krstajic and showed composure beyond his tender years against the Central Americans.
The victory was a relief for Krstajic, who spoke of the pressure he had been under following his appointment.
Yet now his eyes are firmly fixed on their next fixture against Switzerland, who opened their campaign with a surprise draw against Brazil. Victory for Serbia in Kaliningrad on Friday would secure qualification for the last 16.
"With respect to Switzerland, we've analysed all three opponents, we know everything about Switzerland, now we are going to watch for some details when they play Brazil to make sure we have not missed anything."
When Muslin was sacked by the Serbian FA in October, he was quoted as saying they had parted ways because "we don't think alike on how the team should look for the World Cup in Russia."
If Krstajic's bright and enterprising side were not Muslin's vision of the future then many Serbia fans will be glad a change was made.
(Reporting by Toby Davis, editing by Pritha Sarkar)
