"The victory belongs to all the players, they deserve it," Jia told reporters. "Their desire to win has impressed me the most over the year and I've been deeply moved by this. This has given me courage to lead them.
"The battle has just begun and there will be tough games ahead."
China are third in the group behind Spain on goal difference, while leaders Germany have already reached the last-16.
The top two teams from each group automatically qualify for the knockout rounds along with the tournament's four best third-placed teams.
China will automatically advance if they beat Spain and Jia said his team were going into the match as underdogs but would be under less pressure to deliver than their higher-ranked opponents.
"Spain are stronger than us, so we can play without the pressure of expectation which could give us a better performance," he added. "Hopefully our players can unleash their potential and execute the match plan well."
(Reporting by Rohith Nair in Bengaluru; Editing by Simon Jennings)
