Forward Yuma Suzuki headed in the winner Saturday to lift Sint-Truiden to a 2-1 victory over Belgian defending champions Genk.
Suzuki scored his fourth goal of the season late in the first half at Luminus Arena, heading in a cross from Jordan Botaka in the 41st minute.
"It was nice to get a chance," Suzuki said. "The fact that I managed to get through shows our value as a team."
Some excellent saves from Samurai Blue goalkeeper Daniel Schmidt helped seal Sint-Truiden's victory, while Genk's Junya Ito narrowly missed a last-minute shot and was unable to secure a point for the hosts.
"I thought it was in, but it was just a little off," the Japanese midfielder said.
Genk's Mbwana Samatta opened the scoring in the 9th minute before Yohan Boli leveled for the visitors nine minutes later.
Sint-Truiden sits 10th in the Belgian First Division A table with 21 points, while Genk is ahead of Sint-Truiden in ninth on goal difference.
The struggling defending champions have yet to record a win under new manager Hannes Wolf, and are bottom of their group in the Champions League with no hope of reaching the knockout stage.