Rienk Johannes Mast (born 19 July 2001) is a Dutch college basketball player for the Nebraska Cornhuskers. Standing at , Mast usually plays the power forward or center position. He is a current member of the Dutch national basketball team.
After playing korfball first as a kid, Mast switched to basketball for the club Celeritas-Donar from Groningen. After a couple of years, he changed teams to RTC Noord where he was coached by Marco van den Berg. As a youngster, Mast received offers for Real Madrid Baloncesto to play in their program.
Mast played his first professional seasons for Donar, as he was added to the roster for the 2017âÂÂ18 season. When Mast played his first game, he was 16 years old. On 1 February 2018, Mast scored 24 points in a NBB Cup game against Racing Beverwijk, which made him the youngest top scorer for Donar in history. In the 2017âÂÂ18 season, Mast started in 3 of the 29 games he played for Donar and averaged 3.6 points and 2.0 rebounds in the Dutch Basketball League. He played two games in the continental fourth-tier FIBA Europe Cup competition.
In the 2018âÂÂ19 season, Mast had his breakthrough season. Because of personnel changes within Donar and American players leaving, Mast was given a place in the starting five from January. On 12 January, he scored a career-high 30 points in a 101âÂÂ67 win against BAL Weert. In April 2019, he was awarded the DBL MVP Under 23 award, as well as the DBL Most Improved Player award.
On 21 January 2019, it was announced that Mast committed to Bradley University to play for the Braves. He redshirted his freshman season. As a redshirt freshman, Mast averaged 8.6 points and 5.9 rebounds per game. He was named to the Third-team All-Missouri Valley Conference as a sophomore.
In April 2023, after four years at Bradley, Mast announced that he would be transferring to Nebraska, where he would have two years of eligibility remaining. He explained his move by stating that "Bradley is a great basketball spot, [...] but you get to play against high majors 4-5 times a season. I want to see how I match up and play under bright lights every night. I want to see how I stack up against the best competition in college." After playing one year with Nebraska, Mast sat out the entirety of the Nebraska's 2024âÂÂ25 season due to an injury on his left knee that required surgery; he obtained a medical redshirt and was confirmed to be returning to Nebraska the following season.
In 2017, Mast played for the under-16 and the under-18 Netherlands national basketball team. He played at the 2017 FIBA Europe Under-16 Championship Division B, where he reached the final and made the tournament All-Star Team. Mast averaged 11.9 points, 10.1 rebounds and 1.4 assists per game.
In 2018, Mast won the 2018 FIBA Europe Under-18 Championship Division B while being the captain of the Dutch under-18 team. On January 21, he committed to play for the Bradley Braves in NCAA.
On November 16, 2018, Mast was selected by head coach Toon van Helfteren to be a part of the Netherlands senior team for the first time. On November 29, 2018, Mast made his debut for the Netherlands in a 78âÂÂ105 loss to Poland.
|- | style="text-align:left;"| 2019âÂÂ20 | style="text-align:left;"| Bradley | style="text-align:center;" colspan="11"| Redshirt |- | style="text-align:left;"| 2020âÂÂ21 | style="text-align:left;"| Bradley | 28 || 19 || 23.5 || .484 || .359 || .724 || 5.9 || 1.3 || .3 || .5 || 8.6 |- class="sortbottom" | style="text-align:center;" colspan="2"| Career | 28 || 19 || 23.5 || .484 || .359 || .724 || 5.9 || 1.3 || .3 || .5 || 8.6