The rookie went down after a flagrant foul by Aaron Nesmith on a fast break during Indiana's home opener and did not return.
Cooper Flagg's night ended early in Indianapolis on Friday after Pacers wing Aaron Nesmith hit him with a hard foul as Flagg drove for a breakaway dunk in the final minute of the first half. Flagg landed hard and clutched his left shoulder. Officials assessed a flagrant foul and a technical on Nesmith, and a scuffle broke out between the two teams, with Naji Marshall also picking up a technical.
Flagg left after playing 17 minutes, finishing with 14 points, five rebounds, six assists, three steals and one block. The Mavericks ruled him out for the second half with left shoulder soreness, and Marshall took his spot in the starting lineup to open the third quarter. Dallas has not given a further diagnosis or a timetable for his return.
The injury came on a night that was supposed to center on Tyrese Haliburton, who was playing his first home game since tearing his Achilles during Game 7 of last season's NBA Finals. Instead the Mavericks were running away with the game, holding a 77-43 lead in the early going, before the Nesmith foul shifted the focus to Flagg's shoulder.