DOBBIACO, Italy - Six-time Olympic champion Marit Bjoergen won her fourth straight stage in the Tour de Ski on Wednesday, extending her overall lead to more than a minute and a half.
The Norwegian clocked 12 minutes, 48.5 seconds in the 5-kilometre classical individual start race. Norwegian teammate and defending champion Therese Johaug finished second, 10.8 seconds behind, and Heidi Weng, another Norwegian, was third, 13.1 behind.
Seeking to win the Tour for the first time after twice finishing runner-up, Bjoergen now leads Weng by 1:34.3 in the overall standings.
"The shape is good," Bjoergen said. "I'm not getting tired."
It was Bjoergen's sixth consecutive victory overall, including two World Cup wins before the Tour began.
Also, Alexey Poltoranin of Kazakhstan took advantage of different equipment to win the men's fourth stage, while overall leader Petter Northug Jr. had his overall lead reduced to just 1.5 seconds.
Poltoranin, the only top-ranked competitor to use skate skis, finished half a second ahead of Evgeniy Belov of Russia in the 10-kilometre individual start classic leg.
"To double pole the whole competition was a new experience for me," Poltoranin said. "I had great skis, they were very fast. I decided to go on skate skis only 10 minutes before the start."
Martin Sundby of Norway, the defending champion, was third, 4.2 seconds behind.
Sundby closed the overall lead on Northug Jr., who crossed seventh, 22.8 behind.
It marked the first time Northug Jr. has not finished on the podium in this year's Tour. He had entered with a 25.1-second lead over Sundby.
Alex Harvey of St-Ferreol-les-Neiges, Que., finished 14th in Wednesday's race to move into seventrh place overall.
"It was a top-15 so that is good, but not great either," Harvey said. "My first split was a little slow so I think I went a little hard in the middle of the race. I just started losing some energy later in the race."
Devon Kershaw, of Sudbury, Ont., finished 21st while Ivan Babikov, of Canmore, Alta., was 32nd.
Thursday's fifth leg includes men's 35-kilometre and women's 15-kilometre freestyle pursuit races.
The seven-stage Tour concludes on Sunday with the traditional climb up Mount Cermis.