Martins Dukurs of Latvia won all four heats to comfortably retain his skeleton world championship on Friday.

Dukurs led by more than a half-second after the opening day, and extended his advantage to more than a second in the final two heats, setting a track record of 52.09 seconds in the final run.

He sealed his fourth career world title.

Olympic champion Alexander Tretiakov of Russia and Yun Sung-bin, who got South Korea's first-ever skeleton World Cup win two weeks ago, finished 1.13 behind Dukurs to share second place.

Axel Jungk of Germany, who was the only other competitor within a second of Dukurs after the opening day, trailed by 1.87 in fourth.

Canada's Dave Greszczyszyn finished 14th, 3.95 seconds behind. Barrett Martineau was 19th and Evan Neufeldt was 25th.

Earlier, Tina Hermann of Germany built a 0.16-second lead over European champion Janine Flock of Austria in the women's competition, which will be concluded on Saturday.

Both pre-race favourites surged ahead of the field, with third-place Sophia Griebel of Germany already more than a half-second off the pace.

Overall World Cup leader Hermann, who won gold with Germany in the combined bobsled and skeleton event last Sunday, won the opening run and was fourth-fastest in the second.

Her German teammate Griebel, who was fastest in the second run, was 0.53 behind. Anne O'Shea of the United States came another 0.01 back in fourth.

Elena Nikitina of Russia, who won the junior world title here three years ago, was the fastest starter in both heats and finished 0.55 behind Hermann.

Olympic and defending champion Lizzy Yarnold of Britain has taken a year off from the sport.

Elisabeth Vathje of Canada sits in eighth.