RUMFORD (AP) – Olympian Kikkan Randall and unheralded Leif Zimmerman braved frigid cold Thursday to capture the 1-kilometer freestyle sprint titles on the fourth day of racing at the Chevrolet U.S. Cross Country Championships.

Subzero temperatures forced officials to delay the start of the qualifying round by 90 minutes. It was 4 degrees when the races got under way at Black Mountain, and high winds drove the wind chill far below zero throughout the day.

“It felt like skiing across Antarctica in that first straightaway,” said Randall, a 2002 Olympian from Anchorage, Alaska.

Randall out-skied Sigrid Aas, a Norwegian studying at the University of Alaska-Fairbanks, for her second sprint title.

In the men’s final, Zimmerman, a Bozeman, Mont., skier who was fifth a year ago in the sprint at the World Junior Championships, overtook Carl Swenson with about 100 meters to go to win the gold. Swenson had won five straight U.S. title races, including all three previous races since Saturday.

“I wasn’t expecting much,” Zimmerman said. “I just came out to do it.”

The championships help determine berths for the World Junior Championships Feb. 2-7 in Stryn, Norway, and the under-23 World Championships Feb. 11-15 on the Olympic trails at Soldier Hollow, Utah.

Racing concludes Sunday with the long distance races, the men’s 50-kilometer classic and women’s 30-kilometer classic.