A spokesperson for Mizzou basketball confirmed that Jontay Porter re-tore his right ACL and faces a lengthy recovery process again.
Alex Schiffer of the Kansas City Star was the first to report the news.
The injury happened while training in Denver where he was rehabbing.
Porter first tore his right ACL and MCL during an exhibition game before the season that forced him to miss his entire sophomore year.
As a freshman, he was the SEC Co-Sixth Man of the Year and a member of the SEC All-Freshman Team.
Porter averaged 10 points and 7 rebounds per game as a freshman. He appeared in all 33 games for the Tigers in his first season at MU. The former Father Tolton High School standout started for the Tigers seven times.
Porter has not said whether or not he will return to Mizzou for his junior year or go to the NBA Draft. Prior to the second ACL tear, most projections showed Porter as a first-round pick.