Colmar - Slovakia's Peter Sagan kept enough strength in reserve in the hills of Alsace to win a reduced bunch sprint for his 12th overall Tour de France stage win on Wednesday.
France's Julian Alaphilippe held onto the leader's yellow jersey and even had a tilt at the stage win with a downhill charge after the final climb.
Alaphilippe, who was cheered throughout by French fans again Wednesday, will start leader for Thursday's first real mountain test that concludes with a tough summit finish in the Vosges.
"My legs are killing me," said Alaphilippe, who took the overall lead on Monday with a gun-slinging offensive from 15 kilometres.
"Tomorrow is going to be a huge test, for me and everyone," said the 27-year-old former soldier.
Sagan's win will be popular with armchair fans as the charismatic former triple world champion, and six-time green sprint jersey winner, had had two near misses so far.
"I try every day, and then one day you get it," said the burly Sagan.
"I suffered a bit in the climbs. But I had to get into the sprint, I was patient. I'm 47 points ahead in the race for the green jersey now."
Sagan turned on the power from 150 metres out to beat pre-race favourites including Jumbo Visma's Wout van Aert, a breakout star of the race who came second while Italy's Matteo Trentin came third.
Van Aert, riding in his debut Tour since converting from cyclo-cross, closed in to within 14 seconds of the overall lead and maintains his under-25's white jersey as the buzz around him continues to grow.
Defending champion Geraint Thomas and his Team Ineos co-captain Egan Bernal finished safely in the pack in Colmar after a stage that passed through vineyards and villages of picturesque half-timbered houses.
Thomas was typically dry when asked what he expected as the peloton headed off in the morning, saying: "I'm expecting the worst and hoping for the best."
The 2019 Tour, with little time-trialling and mountains galore, should prove a climbers' dream.
On Wednesday, the specialist climbers and those who can keep up in the hills were given a chance to unsheathe their swords on the slopes below the medieval Koenigsberg Chateau, the first category two climb of the Tour.
Welshman Thomas looked relaxed after the race.
"Tomorrow's the big day, that's where it all starts really," the 33-year-old said.
What Thomas describes as 'the big day' is a seven mountain slog culminating in a summit finish at La Planche des Belles Filles where four-time Tour de France winner Chris Froome enjoyed a breakout win in 2012.