Sagan attacked as Demare hit out, but an indecisive line cost him, taking right to follow Fernando Gaviria, then switching to the left to take Demare’s tail in the sprint finish, but was unable to match the Frenchman’s speed, settling for second for Bora Hansgrohe.
Third place went to Alvaro Hodeg from Deceuninck-Quick Step, whilst teammate Joao Almeida was able to finish safely to keep hold of the maglia rosa as overall leader.
A flat 182km stage from Porto Sant’Elpido to Rimini meant it was all to play for with the sprinters, with yesterday’s sensational win from Sagan showing the Slovakian was still in contention against the young Demare for the points classification.
But it was Groupama who had the best leadout and the best sprinter in the grupetto with Demare extending his lead in the maglia ciclamino.
A thrilled Demare said: “Impressive, really impressive. The whole team moved up for me. They had to bring the breakaway back and set a really high pace.
“We had to do well getting through all the tight turns in the town but of course before the finish, everybody did a great job. Jacopo Guarnieri was fantastic. There he was for 400 metres and I was waiting. Then, in the end, I launched the sprint and I knew that people were trying to get around, but I was strongest for the line.
“It feels amazing. Of course, I didn't think I could get four stages here. I was looking for a stage win and I'm so happy. I really want to congratulate the whole team because it's their victory as well. They believed in me, everyone has worked really hard and the work is paying off.”
Overall leader Almeida also remains in the lead in the young rider’s classification, and his Portuguese compatriot Ruben Gurreiro from EF Pro Cycling still managed to keep the mountain’s maglia azzurra jersey.
After a hard graft from UAE Team Emirates, sprinter Gaviria was not even close to challenge for the sprint finishing in seventh – a missed opportunity for the Colombian.
The stage opened quickly, with a five-man break forming 5km from the gun, including Italians Matia Bias, Fabio Mazzucco, Francesco Romano and Marco Frapporti, and Belgian rider Sander Armee.
With about 30km to go, there was a crash involving Italian Elia Viviani who was hit by a motorbike on a roundabout, bringing down several other Cofidis riders, although the Italian was able to get back on for the finish.
Further up the road, Armee and Bais managed to clear the group, with the Belgian rider attacking on a short climb to take a solo lead with 24km to the finish. However, it was a feat just too long for Armee from Lotto Soudal, and he was caught with 6km to go to make it a bunch sprint finish.
The last few kilometres saw the riders take some windy bends on sketchy roads, and go into a tailwind finish, but nothing could phase Demare as the French champion flew across the line a whole bike length ahead of Sagan.