Jessie Diggins competes in her first race at the Beijing Olympics on Saturday, the 15 km skiathlon.

You'll have to stay up very late — or get up very early — to watch it. The race starts at 1:45 a.m. on USA Network, and usually lasts about 40 minutes. (Don't worry, it will be replayed on Ch. 11 at 1 p.m.)

The skiathlon combines classic and freestyle technique in one race. Skiers use classical technique and skis for the first 7.5 kilometers, then switch to freestyle skis and technique for the second half of the race.

Diggins, of Afton, finished fifth in the event four years ago. She has followed a detailed preparation plan leading to her first race at the Beijing Games. Right after Christmas, she competed at the grueling Tour de Ski — a series of six races in eight days — to build fitness for a busy Winter Games schedule. After the Tour, she decamped to Seefeld, Austria, to recover in a lower-altitude environment.

Then it was on to Livigno, Italy, for a final training block at the same altitude as Beijing. Diggins and teammate Julia Kern even raced a simulated skiathlon, a helpful prelude for a type of race that doesn't come around often.

"It was awesome,'' Diggins said. "It was really hard, and I'm so glad we did it.

"We had coaches going nuts, taking video, cheering for us. We had bibs on. We had pits set up. We had everything to simulate it, which was nice, because we don't get to do many skiathlons anymore. It was really cool to practice that pacing at altitude.''

Athletes are expecting to race in extremely low temperatures at the course in Zhangjiakou, 112 miles northwest of Beijing. Thursday's high temperature was 7, and the area is prone to gusty winds.

The U.S. athletes got a dress rehearsal of sorts at November's World Cup opener in Ruka, Finland, another bitterly cold locale. Diggins said they practiced layering their clothing and tested out cold-weather gear like racing gloves and wind-stopping undergarments. She will be "ready for anything'' in Beijing, with lots of clothing options that will allow her to adapt quickly to changing conditions.

"We got a chance to run through it and see how we wanted to handle it,'' she said. ''I feel really good about everyone's preparation.''