The Lille public prosecutor’s office confirmed Monday that it has opened an investigation into "violence with a weapon" after a water bottle was thrown at Mathieu van der Poel during his Paris-Roubaix victory on Sunday.

According to Belgian media, a 28-year-old man turned himself in to police in West Flanders on Monday, admitting to throwing the bottle and expressing regret.

Bottle Thrown From Fan Bus At 40 Kph

Television footage appeared to show the bottle thrown directly at Van der Poel during the cobbled sector in Templeuve, roughly 33 kilometers from the finish in Roubaix.

The man reportedly traveled on a bus chartered by a Belgian fan club for Slovenian rider Matej Mohoric. The group, 'Matej Matjes,' stated via social media that the man is not a member and that they had urged him to contact the authorities.

Van der Poel was incensed after the race. "It is unacceptable," said the Dutch rider. "It was a full bidon. It weighed half a kilo and I was riding at 40 kph. It’s like being hit in the face with a stone."

Alpecin-Deceuninck To File Complaint Over Escalating Abuse

His team, Alpecin-Deceuninck, issued a statement Monday condemning the incident as “dangerous and unacceptable.”

"We are relieved that Mathieu remained unharmed and confirm that, as a team, we will be filing an official complaint against the perpetrator to formally denounce this behavior," the team said.

Van der Poel, a seven-time cyclo-cross world champion, has previously faced abuse at races, including being spat at. The team said the situation is escalating.

"What occurred on Sunday represents an escalation of earlier incidents, with Mathieu van der Poel not being the sole target," the team added. "Such misconduct is either caused by or accompanied by excessive alcohol consumption."

The team emphasized that the safety of riders is at stake, warning that such acts “overshadow the enjoyment and reputation of genuine cycling enthusiasts and divert attention from sporting achievements.”