WATCH: Throwback to Jayson Tatum vs Jalen Brunson in a high school matchup ahead of the Celtics vs Knicks NBA season opener

October 22 means it is finally NBA opening night, with the defending champions, Jayson Tatum and the Boston Celtics, beginning their title defense. Their first opponents are Jalen Brunson and the New York Knicks.

However, before becoming stars in the NBA, the two athletes went against each other way back in 2015, while both were still in high school.

Before the Knicks and the Celtics tipoff, the Courtside Films Instagram page posted a video of Brunson and Tatum's high school clash, which happened in Wheeling, West Virginia.

The pair combined for 87 points, with Tatum having 39 points, 14 rebounds, three assists, two steals and one block, leading his Chaminade High School to victory, 88-81. Meanwhile, Brunson had a game-high 48 points for his team, Stevenson High School (Lincolnshire, Illinois).

When these two met in January 2015, Brunson was already a senior and had already committed to Villanova. He won two NCAA titles with the Wildcats before eventually being drafted by the Dallas Mavericks in 2018.

Meanwhile, Tatum was still a junior who was still entertaining offers. He eventually went to Duke University, spending his freshman year there as a one-and-done before entering the NBA draft in 2017. He was selected by the Boston Celtics and won the NBA championship with the team in 2024.

Jayson Tatum and Jalen Brunson were high school basketball stars

Jayson Tatum had plenty of accolades while playing for Chaminade in Creve Coeur, Missouri, winning plenty of awards since his freshman year. He was named a McDonald's All-American during his senior year in 2016, as well as Mr. Show-Me Basketball and the Gatorade National Player of the Year.

He averaged 29.6 points and 9.1 rebounds during his senior year and won the Missouri Class 5A state championship. He was considered a five-star recruit and ranked the No. 3 overall recruit, just behind Harry Giles and Josh Jackson.

During the 2016 McDonald's All-American Game at the United Center in Chicago, Jayson Tatum had 18 points and eight rebounds in a 114-107 loss for his East team. However, he had a much better outing at the Jordan Brand Classic, scoring 18 points to help the East team win that game.

Before he committed to the Duke Blue Devils, Jayson Tatum's final four choices included North Carolina, Kentucky and Saint Louis University.

As for Jalen Brunson, he was also a 5-star recruit, being ranked No. 16 overall and the No. 1 player in Illinois. He was also regarded as the best point guard in his class, but was the only one ranked in that position, as the class of 2015 was considered to not be a good point guard class.

He was named the Illinois Mr. Basketball, USA Basketball Male Athlete of the Year, and the FIBA Under-19 World Cup MVP, all during his senior year at Stevenson in 2015. Like Jayson Tatum, he was also named a McDonald's All-American during his senior year.

Brunson averaged 23.3 points, 5.2 assists and 4.7 rebounds per game during his senior year, before committing to Villanova where he had one of the most successful college runs for the school.