The Australian held off a late charge from Lewis Hamilton to finish ninth in Korea, fighting his way up from 21st on the grid after being issued a gearbox penalty in qualifying.
Riccardo told Sky Sports News that he was confident of securing a higher finish in the points before having to contend with break failure midway through the race.
He said: "We fought our way into the points and were running eighth with 10 laps to go, when I was struck by a brake problem unfortunately.
"I somehow managed to bring the car home and be fairly strong but unfortunately lost the eighth position.
"I'm still happy. In terms of pure performance, this was our best weekend maybe of the year, or at least for a long time this year."
Riccardo has now scored four points finishes in his last five races to impress a number of teams higher up the grid.