The latest standings see Voeckler’s general classification lead over Cadel Evans cut to one minute and 18 seconds, with Frank Schleck at 1:22, Andy Schleck at 2:26, Samuel Sanchez 2:59 back and Alberto Contador at 3:15 with four stages left.
Meanwhile, Britain’s Mark Cavendish extended his lead in the points classification by crossing the line at the head of the peloton. The HTC-Highroad rider now holds a 35 point lead over Jose Joaquin Reyes in the race to claim the coveted green jersey.
The day belonged to Boasson Hagen, however, who won his and Team Sky’s second stage of the event with a solo attack near the end of the stage from Gap to Pinerolo.
The 24-year-old Norwegian, runner-up to compatriot Thor Hushovd 24 hours earlier, worked himself into a 14-man escape group on the 179-kilometre route as the Tour headed into Italy.
He reached the summit of the Cote de Pramartino with a lead of around 20 seconds and negotiated the 8km descent to win from Bauke Mollema.
“It was a really great day today,” he said. “I felt a bit disappointed yesterday to not win. I really wanted the win today and I really tried to get into the break. My team-mates did a great job to help me get into it.
“It was really hard to get away in the group as risers were chasing behind. Finally we made it away and I was feeling great the whole day.
“I really wanted to win so I got some extra power from that and also from all the Norwegian fans out on the course. It’s so nice to win.
“We did the route in training earlier on this year and I was thinking about this stage. I had a plan and everything was perfect.
“The race goes into some really hard stages now so I will try to save my legs for the time trial (on Saturday).”