Chris Froome put himself back in yellow at the Tour de France, finishing only a second behind stage-14 winner Michael Matthews.
Astana rider Fabio Aru only got his hands on the jersey on stage 12, but fell victim to an untidy race that saw the peloton broken apart on Saturday's 181.5-kilometre route from Blagnac to Rodez.
It was not expected that the race lead would change hands, but reigning champion Froome is once again in prime position to finish top of the pile after turning a six-second deficit into a 18-second advantage.
Matthews' stage victory, sealed on a steep uphill finish, was a suitable reward for an excellent showing from Sunweb, while Olympic road race champion Greg Van Avermaet (BMC Racing) took second.
GOOD DAY/BAD DAY
Sky would not have been too worried about the deficit to Aru before this stage, but nor would they have necessarily been anticipating regaining the maillot jaune from the Italian's grasp quite so quickly.
On a day when the peloton was stretched to breaking point by numerous breaks and some poor coordination - not to mention fatigue within the teams - Astana came off much the worse as Aru finished down the field to hand the initiative back to the irrepressible Froome.
1. Michael Matthews (Sunweb) 4:21:56
2. Greg Van Avermaet (BMC Racing)
3. Edvald Boasson Hagen (Dimension Data) +0:01
4. Philippe Gilbert (Quick-Step Floors) +0.01
5. Jay McCarthy (Bora-Hansgrohe) +0.01
1. Chris Froome (Sky) 59:52:09
2. Fabio Aru (Astana) +0.18
3. Romain Bardet (AG2R La Mondiale) +0:23
1. Marcel Kittel (Quick-Step Floors) 373 points
2. Michael Matthews (Sunweb) 274 points
3. Andre Greipel (Lotto Soudal) 187 points
KING OF THE MOUNTAINS
1. Warren Barguil (Sunweb) 94 points
2. Thomas De Gendt (Lotto Soudal) 36 points
3. Mikel Landa (Sky) 33 points
In its own right, the 189.5km leg from Laissac-Severac l'Eglise to Le Puy-en-Velay is not the toughest course, but the peloton may need reminding of that fact when they hit the climb up the Col de Peyra Taillade, which features gradients of up to 14 per cent to test tired legs. Still, it is the final stage before a much-needed rest day.