Julian Alaphilippe stormed into the yellow jersey as Geraint Thomas lost a handful of seconds to team-mate Egan Bernal on stage three of the Tour de France.
Alaphilippe took yellow off the shoulders of Mike Teunissen as he attacked on the final categorised climb of Monday's 215km stage from Binche to Epernay, while the steep finish in the capital of Champagne country was enough to see Thomas lose the wheel of Ineos team-mate Bernal.
The Welshman will be grateful that Groupama-FDJ's Thibaut Pinot was the only other general classification hopeful to pick up that small slice of time, but though five seconds is a tiny margin, it could prove a significant moment as the co-leaders vie for supremacy within Team Ineos.
"We really had to bust a gut today," Thomas said. "I did feel OK, though. I think this stage will be good for me in the long run.
"I felt OK really, considering that short steep climbs aren't necessarily what I love. But yeah, I think we rode well as a team, we were always in good position and communicating really well, so it's a good day.
"I wasn't dancing up the climbs but it was OK. I didn't really do more than had to be done."
With an individual time trial to come next week there is no immediate cause for concern, but Thomas will be eager to avoid a repeat of what he was able to do to Chris Froome last year, picking up small increments of time until he emerged as Team Sky's clear leader.
Bernal said he did not realise the gap to Thomas had appeared.
"I didn't really know what was going on behind me, so I couldn't see where the other GC guys were," the 22-year-old said.
"All I can say for sure is that it was a really hard day. Alaphilippe was really impressive. I'd tried to follow him with a view to going for the time bonuses, but it was impossible. I think everyone has suffered a lot today."
There were no other notable gaps in the battle for yellow, with all the other major contenders crossing in the Thomas group. While Mitchelton-Scott's Adam Yates was there, his brother Simon shipped more than six minutes.
Thomas ended the day seventh in the nascent general classification standings, 45 seconds down on yellow with the Colombian Bernal in sixth, 40 seconds off Alaphilippe.
The stage victory for the 2018 King of the Mountains was little surprise on a Classics-style stage which seemed ideally suited to the Deceuninck Quick-Step rider's explosive style.
"He may have designed today's stage himself," Mitchelton-Scott sporting director Matt White joked this morning.
"It's like the Amstel Gold Race in a French vineyard."
Even so, Alaphilippe had to execute in order to take his first career yellow jersey and he did so in style.
After waiting patiently over 170 kilometres of flat roads out of Belgium, then over the first three categorised climbs of a lumpy finish, Alaphilippe burst forward on the 12 per cent inclines of the Mutigny inside the last 20 kilometres.
He swept past Lotto-Soudal's Tim Wellens, the last survivor of the breakaway, at the summit and accelerated on the descent just as Jumbo-Visma's Teunissen was being jettisoned.
He had 50 seconds by the foot of the descent, and stayed away over the uncategorised Mont Bernon and the eight per cent gradients of the finish line to win by 26 seconds from Michael Matthews.
"I'm speechless," the 27-year-old said. "I don't realise what's happening to me. I knew this stage suited me.
"I managed to avoid any pitfalls and crashes. I felt good so I accelerated in the Mutigny climb but I didn't think I'd go alone. I gave everything.
"It's difficult to meet the expectations being the favourite. I made it. I'm delighted."
