Much was expected from the cobbled 156.5km stage from Arras Citadelle to Roubaix, which referenced the Paris-Roubaix classics course, and it delivered in spades. The display was tempered though with disappointment for Australian fans when Richie Porte (BMC) crashed out early in the piece.
It was an emotional win for Degenkolb, winning the stage after leading out the bunch sprint from the front of a three-man breakaway to take a famous victory.
“Pure happiness,” said Degenkolb, when asked what was going through his mind when he had won. “I was chasing this victory for so long, and it’s really hard to describe.
"It was a really hard fight the whole day. It’s also a victory of the team. We really had a plan to stay out for the trouble all the time and it really worked out really well. It’s unbelievable.”
The day was bittersweet for BMC, losing its key general classification contender in Porte with their disappointment compounded as his backup Tejay van Garderen who did not cope well on the cobbles.
It took Van Avermaet to give the team some joy, finishing second to a very emotional Degenkolb (Trek-Segafredo) and Yves Lampaert (Quick-Step Floors), extending his stay in the Yellow Jersey.
Van Avermaet actually extended his general classification lead ahead of the rest day, leading Geraint Thomas (Sky) and Philippe Gilbert (Quick-Step Floors) by 43 and 44 seconds respectively.
Behind the leading trio arrived a battered peloton scarred and weathered with dust from the kind of stage rarely seen at the Tour, one which featured 21.7km of cobbled sectors.
The action got started soon after the flag dropped as Omar Fraile (Astana), Thomas De Gendt (Lotto-Soudal), Antwan Tolhoek (LottoNL-Jumbo), Jérôme Cousin and Damien Gaudin (Direct Energie) made the initial break.
Chad Haga (Sunweb), Olivier Le Gac (Groupama-FDJ), Reinhardt Janse van Rensburg (Dimension), Nicolas Edet (Cofidis) and Lilian Calmejane (Direct Energie) bridged across to create a strong opening to the race with a maximum time gap of three minutes and 49 seconds.
Porte was the first victim of the many crashes on the stage, falling with over 140 kilometres remaining in the race and being taken to hospital.
Team Sky put the hammer down with 65km to go as the peloton fractured and at with 50km left van Avermaet (BMC) made his big move before crashes came from defending champion Chris Froome (Sky), Mikel Landa (Movistar) and Rigoberto Uran (EF Education First-Drapac).
The winning moment came when Lampaert accelerated on the cobbled sector of Camphin-en-Pévèle with van Avermaet and Degenkolb latching onto the Belgian champion and riding together through to the finish.