Teunissen made the swift decision to fill in for Groenewegen and earned the honours by outsprinting three-times road race world champion Peter Sagan of Bora-Hansgrohe and Caleb Ewan of Lotto-Soudal, completing the 194.5km loop in Brussels in 4hr 22min 47sec.

Because the crash occurred less than 3km from the finish, Thomas – who swiftly remounted after being forced into a barrier – will not lose time in the overall standings and nor will fellow Team Ineos member Egan Bernal of Colombia, who was also caught up in the accident.

Another potential contender for the general classification yellow jersey, Astana’s Jakob Fuglsang, managed to finish the stage despite a heavy fall 20km from the end that left his face bloodied from a cut over his right eye, earning him a trip to hospital.

The 34-year-old Dane, who had prepared for the Tour by winning the Critérium du Dauphiné, also suffered grazes to his right side and sustained discomfort in his right knee.

Astana announced shortly after the stage that Fuglsang had not suffered any fractures but would require stitches.

Teunissen is the first Dutchman to have earned the yellow jersey at the Tour in 30 years.

Action continues tomorrow with the second stage, a 27.6km time trial in Brussels.