Peter Sagan went into today's dramatic Tour de France stage as one of the big favourites but the Slovakian was unable to keep up with Astana and Lars Boom in the finale. While happy to extend his lead in the points competition, he lamented a big mistake that had cost him the chance to win the race.

When the organizers of the Tour de France devised the 155.5km stage from Ypres in Belgium to Arenberg in France, they were hoping for drama. The stage start was to commemorate the tragedy of World War I, which commenced 100 years ago. The course was designed to traverse nine sectors of cobblestones, an ancient and rough road surface that can be harder than climbing mountains.

Mother nature, however, decided to dump heavy rain on the stage, forcing the race organizers to remove two of the nine original sectors as they were covered in water.

Cannondale Pro Cycling expected a hard day of racing. Peter Sagan, their leader, busy wearing both the Green and White Jerseys as the leader of the points and best young rider competitions, was favored to do well on this day. Sagan was also sitting in second place, only two seconds down on race leader Vincenzo Nibali of Astana. Sagan, as a specialist on cobbles, could both win the stage and take over the yellow jersey.

Cannondale massed at the front leading into the first cobbled sector. They were trying to reduce the three-minute gap and put their man in a safe spot. As they hit the stones, the gap was down to two minutes.

At the intermediate sprint, Cannondale was still at the front, and Sagan led his team over the line.

As the cobbles took their toll on the peloton, the break was reeled in, and Cannondale dropped back, exhausted from their efforts, Sagan stayed with the dwindling front group. Of all Sagan’s closest completion, only two general classification threats remained – race leader Nibali and Nibali’s teammate Jakob Fuglsang.

With 22km () remaining, Belkin’s Lars Boom put in a dig. Sagan and two others followed. Two kilometers () later, thanks to the chasing of Astana, they were caught.

On the final pavé sector, with three Astana’s setting pace and Boom following, an Omega Pharma-Quickstep rider following Boom lost his legs and let a gap open. Since there was only one good line to ride on the road, those behind were stuck. With twelve kilometers remaining, the leading four were gifted a several-second gap. Only Sagan and Fabian Cancellara of Trek had the legs to chase. The gap slowly grew.

Boom dropped the hammer on the last cobbled sector. With six kilometers () remaining and only two Astana’s to chase, he thought this was his moment.

And it was. He won by nineteen seconds over Fuglsang. Sagan won the sprint for fourth; his third fourth place in five days, one minute down, a success and a disappointment. He dropped to third overall, and his chance of taking the race lead dimmed. But he extended his lead in both the Green and White jersey races.

While his face betrayed a dark humor after he crossed the finish line, Sagan seemed more sanguine after receiving his new jerseys at the podium presentation.

“I'm happy that I came safe out of this stage," he said. "I didn't crash, which is good for being able to continue the Tour de France. I've taken some more points over the other sprinters.

"But I'm also a little bit disappointed because I was at the front and I lost the possibility of winning the stage by my own mistake. I was riding a little bit too far behind with Cancellara when an Omega Pharma-Quick Step rider let a bit of a gap in front of us and we never managed to make it back to the front of the race. I guess this is part of a learning process and I've gained some experience in that mistake.

"We tried to close the gap but it was too late. Anyway, I would like to look ahead and think positively about other chances."