China on Basketball World Cup brink after stunning loss
China went down 89-69 to the World Cup debutants in Manila for their second defeat of the tournament, following an opening-day monstering by Serbia.
China must now beat Puerto Rico in their final group game on Wednesday and hope that other results go their way to avoid a first-round exit.
Djordjevic said his players would have to have more fire in their bellies and accused them of lacking "aggressiveness" against South Sudan.
"In moments of difficulty, you have to find your spirit to respond on the floor," he said.
"It cannot be everything on paper -- you have to find it. Those moments are making winning teams."
China, ranked 27th in the world, fell behind early and could find no way back against 62nd-ranked South Sudan.
They finished the first quarter trailing by eight points and fell short when it mattered, being outscored by 10 points in the final quarter.
China's Zhao Rui said he and his teammates "didn't have the same desire as our opponents".
Djordjevic said South Sudan's 15 successful three-point shots made the difference.
"Those are the killers, they're just cutting your legs," he said.
"When you work so hard and you know what is coming and they shoot in your face and just make it happen."
American-born Li Kaier led China in scoring with 22 points.
Li, also known as Minnesota Timberwolves power forward Kyle Anderson, made headlines when he signed up for China's national team after obtaining citizenship last month.
His performance against South Sudan marked an improvement on his tournament debut against Serbia, where he failed to score a single point.
China are now in danger of missing out on the Paris Olympics qualification spot awarded to Asia's highest-placed team at the tournament.
Japan beat Finland for their first win on Sunday night and could qualify for the next round if they beat Australia on Tuesday.
"It's one of the goals -- if we understand it in the right way, it can be a great motivation," said Dordevic.
"It doesn't have to be a pressure, an extra burden on us. We just have to go out there and play our best game.
"I don't know another way."