Belgium's players were surprised, confused and disappointed by the response of their supporters after scraping into the last 16 of Euro 2024 with a goalless draw against Ukraine on Wednesday.
The Red Devils needed only a point from their final Group E match to be sure of a place in the knockout stage, but they could have topped the group with a win.
Instead, having been held by Ukraine in another toothless display, Belgium will have to face France in the next round, thrust into what is widely considered the tougher half of the draw.
Despite those permutations, Belgium opted to protect their point in the closing stages, rather than chase a winner.
So, when the final whistle sounded, the travelling Belgian fans jeered their players instead of joining in the celebrations.
Kevin De Bruyne, the Belgium captain, directed his team-mates back to the dressing room, and the players described their shock to the Belgian media.
"We are qualified and very proud as a group," said Yannick Carrasco. "As a group, we do not understand the reaction of the fans. We find that disappointing.
"We decided together to go to the dressing room, because we don't think the whistling is normal. You cannot forget where Belgium comes from, and now we participate in every tournament."
Jan Vertonghen added: "I was one of the first to go to the fans, because I was genuinely happy with the qualification and wanted to greet them.
"Yes, there is disappointment because we didn't win, but being booed after we qualified... it's the first time I've experienced that.
"De Bruyne then decided to return to the dressing room and go in together. I understand that. He's the captain and can make that decision."
Head coach Domenico Tedesco weighed in, saying: "I am surprised. All that mattered was qualifying.
"We lost the first match, so the conditions were not easy. And after our win against Romania, everyone was happy.
"My players do not understand that we are now being whistled at. This was a difficult opponent. We did everything we could to score. But hey, we have to accept this."
De Bruyne skirted around the issue in his own interview with broadcasters, but he defended Belgium's approach.
"If we go all out for a goal and we lose, what then? You can do that and concede a goal like against England [in March's friendly]," he said.
"France are now waiting. We have to recover well and go all out for that match. We are underdogs there. But if you want to win a European Championship, you have to beat everyone, and now it is France."