Missouri center Jontay Porter has re-injured the knee that kept him out for his entire sophomore season in 2018-19.

Porter tore his right ACL in the preseason against Southern Illinois and had been working to rehab it in time for the 2019 NBA Draft. According to the Kansas City Star, he re-tore the same ligament in Denver during a workout recently.

Porter averaged 9.9 points per game and was the sixth man of the year as a freshman in 2017-18, but a second major injury could throw a wrench into his draft status. He currently stands as the No. 18 overall player in CBS Sports' top-75 prospect rankings for 2019's draft, and the No. 1 player at his position, but a second major knee injury before 20 -- and within the span of a single season -- could be seen by some NBA team's as a red flag.

Porter's older brother, Michael Porter Jr., also struggled to stay healthy at his time at Missouri. He sustained a back injury that limited his college career to only three games, and his draft status tanked as a result. He entered his first and only season with the Tigers as a consensus top-2 prospect, but fell all the way to No. 14 in the 2018 NBA Draft.

Porter could have declared for the NBA Draft after his freshman season but opted to return in hopes of improving his stock and becoming a potential lottery pick. He will have to make the same difficult decision this offseason, and with injury history in mind, he could be a wild card in the first round dependent upon how teams view his medicals and long-term prospects of staying healthy.

If healthy, Porter can be a game-changer. At 6-foot-11, 240 pounds, rim-runners who can stretch the floor by making 3s, finish lobs and protect the paint are a dime a dozen. For some NBA team in the late first-round, the upside may be worth the risk. But with a second knee injury, his stock may take a tumble on some teams' board if they view him as an injury risk.