KRASNAYA POLYANA, Russia — Justyna Kowalczyk dominated her favorite event at the Sochi Olympics on Thursday, winning the women’s cross-country 10-kilometer classical race despite skiing with a fractured foot.

On a warm, sunny day in the Krasnaya Polyana mountains, Kowalczyk led from the first intermediate time in the interval start race and only increased her lead as the race went on. She finished in 28 minutes, 17.8 seconds, beating silver medalist Charlotte Kalla of Sweden by 18.4 seconds.

“It’s something big for me because I broke my foot two weeks ago,” said Kowalczyk, who wept during the flower ceremony. “I was fighting with myself with this injury.”

Therese Johaug of Norway took bronze, 28.3 seconds behind. Four-time Olympic champion Marit Bjoergen tried to keep up with Kowalczyk but tired toward the end and was fifth, 33.4 behind.

Kowalczyk injured her left foot last month and posted a photo of an X-ray on her Facebook page this week showing a small fracture, but said it wouldn’t stop her from competing. It certainly didn’t seem to bother her in her signature event, as the Pole earned her second Olympic gold medal. She won the 30K classical-style mass-start race in Vancouver four years ago, beating Bjoergen in a tight sprint finish.

There was no drama in this one, though, as no one could keep up. Bjoergen was only 1.9 seconds back after 2.3 kilometers, but that gap grew to 9 seconds by the halfway point and the Norwegian simply ran out of steam after that.

The weather was again unseasonably warm for a cross-country race, with the temperature at 12 degrees C (54 F) at the start. Several skiers used short-sleeved shirts, with American duo Sophie Caldwell and Sadie Bjornsen going without any sleeves at all.

Kalla won the 10K race in Vancouver when it was a freestyle event, and showed again that she is now also among the best classical-style skiers. She took silver in the opening 15-kilometer skiathlon as well, behind Bjoergen.

“It’s incredible. I didn’t think I could get a medal at 10 kilometers because it was so tough, but it was tough for everyone,” Kalla said. “You have to fight for every meter (in the soft snow). You don’t have the high speed on the downhills, as we had at the beginning of the championships.”

The race also featured a number of lower-ranked skiers going out after the favorites, with some trudging slowly through the mushy snow in the sunlight.

Farzaneh Rezasoltani of Iran was more than 14 minutes behind Kowalczyk, while Ivana Kovacevic of Serbia was last, going so slowly up the final hill that race officials could walk alongside her. She finished more than 17 minutes behind.