Holland's Lars Boom prevailed amid the carnage which saw defending champion Chris Froome abandon the Tour de France to win a thrilling fifth stage over the cobbles of northern France on Wednesday.
The Ypres to Arenburg Porte du Hinaut stage commemorated 100 years since the start of World War One and featured many of the cobbles used in the Paris-Roubaix one-day race 'the Hell of the North'.
Wet weather forced race organisers to remove two of the nine cobbled sections, but Froome's falls came prior to the first, where the day's racing drama began.
Boom (Belkin) was in the day's breakaway and proved the strongest over the cobbles on an epic day's racing to win by 19 seconds from Vincenzo Nibali and his Astana team-mate Jakob Fuglsang.
It was a sensational ride from the Italian as he preserved his place in the leader's yellow jersey, by two seconds from Fuglsang and 44 seconds from Peter Sagan (Cannondale).
Race organisers removed sectors seven and five - two sections totalling 2.4-kilometres - reducing the stage distance to 152.5km, 3km less than originally planned.
Froome's exit came prior to the first cobbled section, after around 70km, with seven riders in the early breakaway.
Rein Taaramae (Cofidis) lost contact with his fellow escapees on the first cobbled section, but a 16-rider group formed with 25km, and four cobbled sections, to go.
It included Nibali, Sagan, Boom and Fabian Cancellara (Trek), many people's tip for the stage win.
Two-time winner Alberto Contador was over a minute behind, but as the 16-rider lead group was stretched and then joined back together in a frantic period, the Spaniard lost further ground.
Nibali's rivals continually tried to shed him from the group, but the Italian dug deep to stick with them and his team-mates Lieuwe Westra and Fuglsang did a sterling job at the front.
Geraint Thomas and Richie Porte, Team Sky's leader after Froome's withdrawal, tried to bridge the gap by escaping from the Contador group, the Welshman dragging along the Australian.
The Astana trio went ahead with Belkin's Lars Boom with 12km to go before Westra fell away from the leading group with 8km left.
Boom held a commanding lead as the riders exited the final cobbled section and soloed to victory as Nibali enhanced his advantage with support from Fuglsang.
Sagan led the second group home in fourth, 1min 01sec behind Boom, and Porte finished 20th, 2:11 behind, to move up to eighth overall, 1:54 behind Nibali.
Boom was delighted.
"This was an epic stage," Boom said on letour.com. "This morning, when I saw the weather, I smiled a bit.
"For many years, I've dreamt of a wet Paris-Roubaix and I got what I wanted today at the Tour de France.
"It was a crazy race with all the crashes but I stayed at the front, out of trouble.
"It was an amazing feeling. I've been unlucky earlier this year. I had a broken elbow. This win is what I needed for my career."
Contador was 37th, 2:54 behind, to fall to 19th overall, 2:37 adrift ahead of Thursday's 194km sixth stage through Champagne country, from Arras to Reims.
The sixth stage is expected to end in a sprint, meaning Nibali should retain the maillot jaune he won in Sheffield for another day.
"I'm delighted with the outcome of today's stage," the Italian champion said on letour.com.
"It was a really stressful day and a very hard race. I wasn't thinking of the yellow jersey. I was just focused on riding the best I could.
"I'll keep my feet on the ground. I want to remain quiet.
"It's still a long way away with lots of mountains and everybody has seen today that crashes can happen."