The big German sprint ace raised a glass of champagne after winning Thursday's sixth stage at a canter.
The big German sprint ace raised a glass of champagne after winning Thursday's sixth stage at a canter, having already tasted victory on Sunday's second stage.
And ahead of Friday's flat 213.5km seventh stage from Troyes in Champagne to Nuits Saint Georges in Bourgogne, the Tour's top fast men will be asking themselves how to beat the 29-year-old vintage sprinter.
"Kittel is the fastest rider in the Tour. We know it for some years now he's been the fastest," said Norway's Alexander Kristoff, who was third on Thursday.
Kittel was the dominant sprinter on the 2013 and 2014 Tours before missing the 2015 edition due to illness and injury, when his fellow German Andre Greipel proved the master.
Last year, Kittel was back but his Quick-Step train failed to control the chaotic mass finishes and he won only one stage, while the more cunning Mark Cavendish claimed four.
But this year, it is already clear that Kittel is back to his best and the acceleration he produced to storm up from around seventh or eighth place to the head of the pack on Thursday showed he was on a different level to the competition.
Yet he can be caught out, as happened in Tuesday's fourth stage when he was held up by a crash in the final kilometre before rolling over the line 13th, as Frenchman Arnaud Demare won.
And Demare, unlike Kristoff, is unbowed by Kittel's apparent superiority.
"There are more sprints to come, I'll take my revenge tomorrow (Friday)," he'd said following the sixth stage, where he had to squeeze down an almost imperceptible gap next to the safety barriers alongside Norwegian Edvald Boasson Hagen in order to contest the sprint.
"Second's not too bad, I only just scraped through a mouse hole," added Demare.
"I was going very quickly, I was in contention for the win. But Kittel also arrived at top speed."
However for several other sprinters, the bigger issue is not so much beating Kittel as simply staying safe and upright.
Tempers have flared, in particular between Demare and his compatriot Nacer Bouhanni.
On Tuesday, Bouhanni complained Demare had cut across his path in the sprint finish, on Thursday Demare's FDJ team-mate Jacopo Guarnieri accused Bouhanni, of Cofidis, of sticking his knee into him.
"He's probably upset with us because he always loses," said Guarnieri after Bouhanni could manage only fourth.
Demare and Bouhanni will likely have another chance to sprint for the win on Friday, as temperatures soar once again into the mid thirties Celsius, but beating Kittel is proving a tough ask for everyone.