"It came to our attention during Rashard Lewis' physical that he is in need of a medical procedure on his right knee," Mavs president of basketball operations Donnie Nelson said in a statement released by the team. "We wish him all the best for a speedy recovery and continued success in his remarkable career."
Lewis signed a one-year contract for the veteran's minimum with the Mavs last week.
Agent Tony Dutt said they aren't certain yet about the severity of the injury or how long Lewis will be sidelined.
The Mavs signed the 34-year-old Lewis, a 16-year veteran, to back up Dirk Nowitzki at power forward. The two-time All-Star averaged 4.5 points and 1.8 rebounds in 16.2 minutes per game for the Miami Heat last season, primarily coming off the bench.