The 24-year-old Frenchman was the undoubted victor on a day where the general classification battle was largely quiescent, as least partly due to heat and furious racing from the gun. Calmejane attacked solo with 18km to go and held off a surging Robert Gesink (LottoNL-Jumbo) to take the stage.
Calmejane told reporters that the team had decided to go on the offensive and it had clearly paid off. In fact, it seemed that Calmejane's biggest obstacle could have been his own body, with a cramp afflicting him in the closing kilometres.
"I got a bit scared when I cramped between six and four kilometres to go but I had the experience of the same thing happening at Tour de l'Ain last year and I knew what to do," he added.
Chaser Gesink admitted that he wasn't able to take advantage of Calmejane's cramp.
“I was not that fresh anymore myself. I had loads of energy, but by that time it was all gone,” said Gesink.
“It was a tough day. On the last climb, I tried to close the gap at once. I just could not close the gap to Calmejane. Then I exploded a bit."
Calmejane suggested that veteran teammate and breakaway specialist Thomas Voeckler may have been something of an inspiration to him.
“The year I started cycling was in 2004, which was the year that Thomas Voeckler had his first yellow jersey,” he said. “Now that I know Thomas I have a lot of respect for him and he has helped me a lot in my first years as a professional.
"I started cycling admiring Thomas Voeckler and now I get to share this moment with him.”
Calmejane's exploits earned him the polka-dot jersey, but he was sanguine about his chances to keep the maillot pois.
"There are a lot of points tomorrow, so the [polka dot] jersey will be on someone else's shoulders," he said. "I'll be in the unknown after spending so much energy today, maybe a bit more than the other riders.
"But, later on in the race and in years to come, the polka dot jersey could become a goal because the points scale makes it accessible to attackers as well as pure climbers.”