Astana’s Jakob Fuglsang leapfrogging Porte in a thrilling final to the Dauphine after attacking the final climb to the Plateau de Solaison to win by 10 bonus seconds in the overall classification.
Porte, who had lost ground on the penultimate ascent, clawed his way back, but he came up just short.
The result left there BMC captain hurting but he said his overall performance gave him confidence that he could do well at the Tour de France.
"I think I showed in the end that I'm going well and I'm on track for July. It's bitterly disappointing to lose it by such a small margin but credit to Jakob Fuglsang,” Porte said after the stage.
“I think I was up against it from kilometre zero as it seems there were a few guys who preferred to see me lose the race and they lose their podium as well. I don't know what you can really learn from a stage like that. I guess that's racing but bring on July."
"I found myself without a crew, isolated. It was a little against me. I could have done with a couple more teammates up there today. It was me against everyone there for a little bit. You don't forget that for July. It was a solid race.
"I can definitely take confidence out of the race in general. I know my form is there and of course, it would have been nice to finish it off today, but it's definitely good signs for the Tour de France."
The Tour de France starts on 1 July from Dusseldorf, Germany. All stages will be broadcast live on SBS.