La Motte-Servolex - Australian Richie Porte of the BMC team took the Criterium du Dauphine yellow jersey after Friday's sixth stage won by Astana's Danish rider Jakob Fuglsang.
Fuglsang, Porte and overall favourite Chris Froome, came through the line in a photo-finish after the descent of the beyond category mountain Mont du Chat at the end of the 147.5km stage.
"This is my first WorldTour win and I thought I'd come second," admitted the winner after the race.
"Thankfully there was wind right at the end and that stopped Porte getting ahead."
Former team-mates Porte and Froome built up a healthy lead on their rivals - Alberto Contador, Alejandro Valverde and Romain Bardet - on the mountain's punishing climb of 8.7km at more than 10 percent gradient.
"The objective here is to win the race," said Porte. "So when I heard Contador and Valverde had been dropped I picked up the tempo," said the Australian.
Defending champion Froome was happy to test his legs on the gruelling Mont du Chat climb which will also feature on the Tour de France.
"I still have work to do but things are going in the right direction. The climb today showed I'm on the right track for July," said the three-time Tour de France winner.
But the Sky rider was less than satisfied with his position after Friday's stage.
"I'd be lying if I said I was satisfied with my place," said the Briton.
"I wanted to win the stage but I made mistakes. I did a little too much work to catch Fuglsang and I launched the sprint too far out.
"But altogether I'm happy with the way things went. It could have been worse. My legs are good and I'm happy to have been with Richie (Porte) who is in great form.
Contador was happy with the attack.
"I'm not on form yet so the more they attack me the better," said the Spaniard. "I couldn't make the necessary explosive change of pace to keep up on the climb.
"I almost fell on the way down too so I also lost Valverde's wheel."
Fuglsang, a silver medallist in the road race event at last year's Rio Olympics, stayed with the high-profile duo for the technical descent and was adjudged victor at La Motte-Servolex.
Porte now enjoys a 39-second lead over Froome in the general standings, with Fuglsang at 1min 15sec.
Saturday's seventh stage is a challenging 168km ride from Aosta to the epic Alpe d'Huez climb and summit finish via the Col de Sarenne.
Results and standings after the sixth stage of the Criterium du Dauphine a 147km run to La Motte-Servolex:
1. Jakob Fuglsang (DEN/AST) 3hrs 41min 48sec, 2. Richie Porte (AUS/BMC) same time, 3. Chris Froome (GBR/SKY) s.t., 4. Fabio Aru (ITA/AST) s.t., 5. Alejandro Valverde (ESP/MOV) at 50, 6. Dan Martin (IRL/QST) 50, 7. Romain Bardet (FRA/ALM) 50, 8. Olivier Naesen (BEL/ALM) 1min 06sec, 9. Alberto Contador (ESP/TRE) 1:06, 10. Emanuel Buchmann (GER/BOR) 1:14.
1. Richie Porte (AUS/BMC) 20hrs 52min 34sec, 2. Chris Froome (GBR/SKY) at 39, 3. Jakob Fuglsang (DEN/AST) 1:15, 4. Alejandro Valverde (ESP/MOV) 1:20, 5. Fabio Aru (ITA/AST) 1:24, 6. Alberto Contador (ESP/TRE) 1:47, 7. Dan Martin (IRL/QST) 2:14, 8. Emanuel Buchmann (GER/BOR) 2:30, 9. Romain Bardet (FRA/ALM) 2:49, 10. Rafael Valls (ESP/LOT) 3:16.