Mauro Schmidt (Quick Step-Alphavinil) and Tim Wellens (Lotto Soudal), wearing the blue leader's jersey, are separated by just one second. A key part of the 179.9km route from Gingerom to Bellingen is the final golden kilometer sprint, but a controversial move by Schmidt's teammate Yves Lampère disrupted the expected direct confrontation.

Wellens took the first three seconds at the front to take the provisional lead. Schmidt took two seconds in the next two sprints to regain the lead. Behind him, Wellens was blocked not once, but twice by Lampert, who was caught on television cameras blocking his progress; at the third sprint point, Lampert was seen leaning over and bumping into Wellens' shoulder.

It was Quick Step's Florian Seneschal, who fought for valuable time with teammate Schmidt, who took the points in the final two intermediate sprints.

"Yeah, this cost me the Tour of Belgium victory. It's frustrating, but I think I can say I did everything I could to win," said Wellens, who oozed frustration at the finish and said Lemper's shoulder barge was a factor in his loss of the win.

A little more than two hours after the stage ended, the UCI Commissaire confirmed in a communiqué that Lampaert had indeed been disqualified and fined CHF 200 for "deviating from the chosen course, thereby obstructing or endangering other riders and sprinting erratically."

"It was quite a push and shove on both sides.

Lampaert, who had won the stage 3 time trial and was in eighth place overall, told Wielerfritz,

"It was a very good race.

"It may have looked a little flashy on video, but this is racing. Before the first sprint, I myself was pushed a few times by the Lotto Soudal riders."

Wellens explained after the race that even if Lampert had been disqualified, it would have made no difference in the end. He said that the Lotto-Soudal team controlled the race all day, but that the team did everything possible to win and "that's the reality."

"As a team, we did everything we could to win the overall and be in perfect position for the Golden Kilometers. Arnaud de Rey perfected me in the first sprint. The goal was to go full on in the first sprint and focus on Schmidt's wheel. After the first sprint it looked like I was doing really well, but then things went wrong in the second sprint. That move by Lampaert cost him the overall win, but of course his disqualification doesn't change anything," he said in a team statement. "You could say that he lost the Belgian Tour in the time trial and the Ardennes stage: ...... In any case, it was a really exciting battle and a lot of fun for the fans. Losing by such a small margin is never a good thing, but as a team we are proud to have raced in the Belgian Tour and this gives us confidence for the future."[19

Schmidt was 26 seconds behind the GC leader going into stage 4. Schmidt, who earned a 3-second bonus time in the Golden Kilometer sprint, added another bonus time for second place in the stage, jumping up from sixth place. The gap to Wellens in the time trial was several hundred seconds, making him the race leader by this margin.

Race organizers had said that the Golden Kilometer would "spice things up," and that is exactly what happened. By the time chaos broke out around Wellens, Schmidt was several bike lengths ahead and focused on the sprint.

"I didn't see it. Of course I didn't want that to happen. I don't know what happened. But I think both teams did everything they could to take second place," 22-year-old Schmidt told Eurosport after the stage.

"I made a mistake in the first of the three sprints. I opened a gap on the roundabout. I wasn't focused and I jumped. Then I thought, 'Oh my God, it's over. I think I lost it [the GC]. I tried to stay calm."

After taking the decisive seconds with 5km to go to the finish line, Quick Step changed gears and Fabio Jacobsen held off Jasper Philippsen (Alpecin Phoenix) and Gerben Thyssen (Intermarque Wanty-Gobert Materio). He easily finished ahead of the rest of the field. Schmidt said it was a special day because the team focused on his effort on GC, which was the first overall win of his career, not on Jacobsen, the sprinter.

"I felt a little pressure on my shoulders today, but I think everyone believed in me. And it's even better for me that Fabio [Jacobsen] was able to win. He basically said, "The most important thing is to win the GC." I had his full support in the sprint, so he was on his own, but he still managed to win.