Jasper Stuyven attacked in the front group with 17 km to go and and held off a determined chase to claim victory at Kuurne-Brussels-Kurrne.
The 23-year-old Trek-Segafredo rider held a 16 second gap over the remnants of the chasing group to start the final 15-kilometer circuit in Kuurne and held that to the finish.
After Stuyven had claimed the victory, Katusha's Alexander Kristoff won the bunch sprint for second ahead of Nacer Bouhanni (Cofidis).
"Boy (Van Poppel) did a perfect job, he was incredible to keep our group going," Stuyven said. "He was so strong. But the peloton was coming back, so Dirk (Demol, Trek-Segafredo director) said to try something, so I went and I was alone. I just powered through.
"Normally, I am not the man for solo rides; I surprised myself. But in the first lap I really paid attention to the wind, so when I went I knew what to expect and I just gave my all. I thought that maybe Tom (Boonen) would join me because he was very active, and I also knew that he would keep the group turning behind, so I knew I was in for a hard one."