The Australian from Tasmania rode in team BMC Racing’s wings and attacked as the road kicked up to the fortified town.
“I thought it was going to be more [Greg] Van Avermaet and the others, but Richie Porte… It shows that he’s going to be aggressive and he’s certainly going very well,” Sky’s Geraint Thomas, who’s leading the race, said.
“He’s certainly going to be one of the biggest threats and one to watch. I said from the start, he’s the main man and he re-reinforced that today.”
Porte served Sky for four years and helped Bradley Wiggins and Chris Froome win the Tour. He joined BMC Racing for the 2016 season and has extended his stay with team beyond this year.
He won the time trial stage and looked convincing throughout the Critérium du Dauphiné, the pre-Tour warm-up race this June.
Only on the last day did he and the team slip under multiple attacks and Jakob Fuglsang (Astana) rode clear for the overall win.
Froome singled him out as the man to beat for the Tour de France, while Porte said that Sky and Froome were playing mind games with him, and that Froome remains the Tour favourite.
Much will be known after La Planche des Belles Filles summit finish on stage five.
“He needs to gain some time back on Froomey and G, I don’t know where, but he’s going to ride aggressive for sure,” Sky sports director Nicolas Portal said.
“Is he the top rival? I don’t like this question! I’d say probably yes, though.”
Michal Kwiatkowski led Froome and Thomas to the finishing ninth and eighth respectively.
“I think we can expect he’ll [Porte] definitely go for it on the climbs,” Froome added after he warmed down on the rollers.
“He has a bit of time to make up, all the GC guys, have a bit of time to make up on Geraint Thomas, so I think we can expect a very aggressive race once we get into the climbs.”
After losing time in the opening time trial, that Thomas won, Porte must be aggressive to have a chance to win the 2017 Tour de France.
Froome considers it a big task for Porte to already gain the leader’s yellow jersey on stage five, which climbs 5.9 kilometres to the finish.
“He’s have to make up 35 seconds on me and 45 on G, that’s definitely going to take some doing on a six-K climb.”