Froome, who already counts three titles, took over the yellow top from team helper Thomas on Wednesday off the coattails of BMC's work.
"I'd never climbed it before but of course I saw that last climb on the Internet when Chris (Froome) won in 2012 and Nibali in 2014, so that's why I chose to attack with 3km to go", said Aru.
"It's a pity I couldn't finish it off. Then I just had to pray that the door opened on the right-hand side so that I could pass him - and it was just enough". I'm in a great shape.
"I was really confident in my team", Kittel said.
But the race officials were not the only ones squinting at the images from the line trying to determine who had won.
Froome said the stage wasn't as easy as it looked, under the searing sun. "When there's a photo finish, you have your doubts". It can be really close.
"But I learnt a lot from it and promised myself I'd come back as soon as possible to the Tour because I love the Tour".
Britain's Daniel McLay impressed again, finishing in 10th place. "I'm so happy about it and I'm enjoying every minute of it". Fast forward to 2017 and even though he says his battle for the overall is now on hold, Thomas is hoping for a better result. "I just need to trust myself more".
And after a calmer end to an eventful week, the eyes of the main contenders for the general classification were set on an upcoming battle royale this weekend.
The International Cycling Union WorldTour race is due continue tomorrow, with a 187km hilly stage from Dole to Station des Rousses.
But on Sunday's stage, with a trio of Hors Categorie climbs in the Jura - ascents so hard they forcibly remain outside the organisers' ranking of climbing difficulty - there will be no room for those sorts of doubts. "That's what we spend all season training for".
"We all know if we can get a good result with the team we have here". There is always the possibility, however, that Froome will hammer his rivals with one big blow like he did in the ascent to La Pierre Saint Martin in 2015.