That changed in a hurry on Wednesday as Brennan took third place in the 1.3-kilometer classic sprint race, her first race of the week.
Brennan, a former member of the Park City Nordic Ski Club and former University of New Hampshire skier, now trains with the Alaska Pacific University (APU) Nordic Ski Team in Anchorage.
Though Brennan grew up in Park City, she didn't think she had an advantage on the Soldier Hollow course.
"I've skied it a fair bit," she said. "But it's sort of an iconic course, so most of the racers here have skied it a couple times."
After racing in the quarterfinals and semifinals less than an hour before, she said it took her a while to shake her fatigue in the final and get in a groove.
"I was pretty tired," she said. "But I sort of warmed up into it and was able to pick up the pace a little bit going over the last hill."
Brennan finished behind race-winner Jennie Bender of the Central Cross Country team and Sadie Bjornsen, a fellow member of APU Nordic Ski Team.
Bender narrowly edged Bjornsen, finishing with a time of three minutes, 20.2 seconds to Bjornsen's mark of 3:20.5. Brennan finished in 3:21.7.
Park City Nordi Ski Club alum Elizabeth Guiney finished in second place in the women's "B" finals, taking seventh place overall.
Torin Koos of the Bridger Ski Foundation took first place in the men's senior race with a time of 2:51.8.
Brennan was to participate in Friday's 10-kilometer free individual-start event, which took place after this issue went to press. She'll participate in one more distance race on Sunday, and thinks she'll perform even better in the longer races.
"Generally, I'm stronger at distance racing," she said. "So to medal in a sprint is a good sign for the future."
Brennan said the weather on Wednesday was perfect for skiing and the course was well maintained.
"It's great. They always do an incredible job preparing the courses here," she said. "They're so well groomed."
In the junior races, Leah Lange of the PC Nordic Ski Club advanced to the quarterfinal round of the 1.3K sprint before seeing her day come to an end.
The 14-year-old racer said she didn't have anything left in the tank after the morning's preliminary race.
"I thought it was good at the beginning. My prelim was pretty good," she said. "I just didn't have any kick in the quarterfinals."
Much like Brennan, Lange said she expects more from herself in the longer races.
"I hope to do well at those," she said. "Distance is my thing."
Sunday's classic mass-start event begins at 10 a.m. The men will race 30 kilometers, the women will race 20 kilometers, the junior men will race 10 kilometers and the junior women will race five kilometers.