Campbell was proving a nuisance, and only a last-ditch challenge from Nikola Milenkovic prevented Costa Rica's substitute from getting in on goal.
After Costa Rica midfielder David Guzman was handed a yellow card, Kolarov stepped up and curled his shot over the wall and into the net in the 56th minute.
"In the last 15 minutes I had to change a couple of shorts", he said of the nervous conclusion to Serbia's win over Costa Rica. The lineups of both the teams will be announced much before the match starts.
Southampton's Dusan Tadic, Manchester United's Nemanja Matic and Crystal Palace's Luka Milivojevic will be the central midfield triumvirate looking to produce the creativity for the aforementioned Mitrovic, as Serbia try to show their quality and kick off with a win.
But just over 10 minutes into the second half, Aleksandar Kolarov finally broke through.
The former Chelsea defender made his 104th worldwide appearance, surpassing the previous record of 103 by former midfielder Dejan Stankovic.
The 44-year-old admitted he had been under pressure in the build-up to the game.
"Everyone would love to see the national team go far".
SkyBet gives an odd of 10/11 in favor of Serbia and 19/5 on Costa Rica. He was replaced on the roster by Kenner Gutierrez.
Their opponents in Samara famously reached the quarter-finals four years ago after topping a group including former winners England, Italy and Uruguay. "Some of us are repeating, but there are teammates who are playing their first World Cup".