Mastrov debuted for the
California Golden Bears off the bench on February 5, 2021, scoring a career-high 20 points including four made
threes in a 51–62 loss to
Utah. She was California's highest-ever debutante scorer and the team's top single-game scorer against a Pac-12 opponent at that point in the
2021–21 season. She started the last five games of her freshman season, averaging 7.0 points and 4.3 rebounds per game. She shot 4-for-7 for a season-high 11 points in an 88–52 win over
Florida A&M on December 18, 2022. She scored 10 points and grabbed 5 rebounds in a 61–49 loss to
Washington State in the first round of the
Pac-12 Conference tournament on March 1, 2023. She scored 14 points shooting 6-for-8 with two threes in a season-opening 89–56 win over
CSU Bakersfield on November 6, 2023. She averaged 3.0 points and 1.4 rebounds in 13.7 minutes per game for her career. ==Career statistics==