Porte finished second to stage winner and new race leader Chris Froome (Team Sky) at Vaujany, with Contador fading to fifth at 21 seconds. Froome now leads Porte by seven seconds, with Contador in third a further 20 seconds in arrears.
"To be honest it was better than expected. It was a hard day and fast and today showed I'm in good place," Porte said of his second place.
"That I could go with Froome like that is a good sign for me."
Froome had looked in difficultly on the lower slopes of the climb and was spotted near the back of the peloton while Tinkoff set the pace for Contador.
When an attack featuring Contador, Porte and Dan Martin went clear, though, it was Froome who closed the gap.
Inside the final three kilometres Froome unleashed a blistering attack. Contador was the first to follow with Porte and Martin in tow. The Irishman and Contador quickly lost contact, with Porte the only rider able to hold his former teammate’s wheel.
When asked if he was surprised to see Contador dropped, the Australian played down the situation, insisting that the race was far from over.
"I guess so, but it's still not July and with Alberto you have to give him respect and he will come out tomorrow absolutely swinging. For the moment, I’ll enjoy this, it’s a good result and it gives me faith in the work I’m doing.
"I knew that it was hard from 6.2 kilometres. When Froome attacked like that and guys cracked, it gives you a bit more inspiration to carry on."
When Froome attacked, Porte was told not to work with the Team Sky leader. Porte followed the instructions until the final few hundred meters, when a long turn on the front brought them to the line. Froome’s final turn was ferocious and Porte was unable to contend for the win.
"I was being told not to work with him by the team. In the heat of the moment, and we had a good gap, so I did collaborate with him. We still put good time into the other rivals."
After today’s showing it looks as though the race will come down to a two-man battle between Froome and Porte. However recent Dauphine’s have shown that surprises can follow at every turn, and after defending for several days Contador will certainly attempt to go on the offensive over the final two days.
"Tomorrow is a queen stage, so the goal is it recover as much as possible. Tomorrow we'll see what everyone wants to do. Tinkoff controlled that well today but I think Sky has the team to attack like that and it's set Froome up really well, and I benefited from that too.”