ZHANGJIAKOU, CHINA — Jessie Diggins didn't win a medal Saturday in her first race of the Beijing Olympics. That was hard to tell from her upbeat mood after a sixth-place finish in the women's 15-kilometer skiathlon.

Diggins raved about the course at Zhangjiakou National Cross-Country Skiing Centre. She talked about how excited she was to get started on her third Olympic Games. Her skis, her pacing and her conditioning were right where she wanted them, helping her record the day's fastest time in the freestyle portion of the race.

Even the frigid temperatures — 16 degrees with a wind chill of minus-2 at the start — didn't bother Diggins. The conditions certainly didn't slow down Therese Johaug of Norway, who dusted the field by more than 30 seconds to win the first gold medal awarded at the Beijing Olympics.

Johaug finished in 44 minutes, 13.7 seconds for her fourth career Olympic medal. Natalia Nepryaeva of Russia was second, 30.2 seconds behind, and Austria's Teresa Stadlober was third, missing silver by only .3 of a second.

The skiathlon combines both styles of cross-country skiing, with the first half done in classic technique and the second half in freestyle. Diggins finished 50.5 seconds behind Johaug in a time of 45:04.2, moving up a few spots with that swift back half.

"I definitely wish I had a better classic half," she said. "But the skate half was some of the best racing of my life, especially at altitude.

"I'm really, really happy. I'm pumped to see what I can do the rest of the week, but I'm also really proud of that race."

Diggins' teammate Rosie Brennan, who finished 14th, called the conditions "brutal." Athletes wore multiple layers of clothing and still felt the cold, even as they pushed their bodies to the limit.

Most of the field had never raced on the Beijing courses. Because of the pandemic, events to test out the newly constructed tracks were canceled, adding an extra element of mystery to the Olympics. After her first practices in Zhangjiakou, Diggins said she really liked the courses, and she expected the layout and the snow quality would make for fair racing.

Saturday's race didn't change her mind, but Diggins added that the skiathlon track was "definitely as hard as it looks." Johaug, a 14-time world champion who had never won Olympic gold in an individual event, broke away from the field before the halfway point.

A few days earlier, Johaug was worried about staying healthy and making the race. The Norwegian cross-country team had several members test positive for COVID-19 at a pre-Olympic training camp, and she was afraid she might get infected. But her strong classic skiing set her up for the victory.

Diggins was just outside the top 10 for much of the classic portion. She had moved up to 10th at the midpoint, when skiers glide into a pit stop and change their skis.

Armed with a pair of very fast freestyle skis, she began moving up.

"I had amazing skate skis, and I think I paced it just well enough," she said. "I crossed the line with nothing left, which was my biggest goal."

Diggins had a time of 21:01.8 for the freestyle half of the race. That was about seven seconds better than Johaug's time for the segment, which ranked second.

Next up for Diggins will likely be Tuesday's freestyle sprint.

"I feel really good about the pacing and where my fitness is, both mentally and physically," she said. "Overall, I feel this was a really encouraging start to the Games."