Duncan's milestone rebound came on the defensive end with six minutes, 56 seconds remaining in the first quarter after Mike Dunleavy Jr. missed a jump shot.
This was Duncan's second major achievement in as many weeks. He became the fifth player in the history of the league to record 3,000 career blocks Feb. 27, and he continues to rise up that leaderboard.
Vincent Goodwill of CSN Chicago took note of Duncan's achievement as well as his other skills around the rim:
Vincent Goodwill @vgoodwill
Tim Duncan just passed the 15K career mark in rebounds. And is still a top-5 rim protector3/11/2016, 1:25:49 AM
For the first 13 years of his career, Duncan averaged double figures in rebounds, and he recorded more than 12 boards per game in five seasons. He also led the league in total rebounds with 1,042 in 2001-02.
The NBA's active leader in career rebounds came into Thursday's game averaging a career-low 7.5 rebounds per game, though the 39-year-old is playing only 25.1 minutes per contest. He is averaging 10.8 rebounds per 36 minutes this season.
Duncan has been a consistent all-around star for his entire career, and his rebounding accolades show how much work he has put into both ends of the court.
Stats courtesy of Basketball-Reference.com.