Danny Green will be re-evaluated in two weeks after an MRI confirmed he strained his right calf, the Philadelphia 76ers said on Saturday.
The injury occurred during the Sixers' victory over the Atlanta Hawks in Game 3 on Friday night.
The veteran will miss the rest of this series, and could return in the next round, if Philadelphia advances.
Green left with 8 minutes, 15 seconds remaining in the first quarter with Philadelphia up 6-4 and was replaced by Matisse Thybulle.
He returned to the bench in the second half wearing a boot on his right leg.
The three-time NBA champion averaged 4.5 points through the first two games of the second round, shooting just 1-for-9 from 3, but dished a career-high eight assists in Philadelphia's 118-102 win in Game 2 to help even the series.
Thybulle finished with seven points, Furkan Korkmaz set a career playoff high with 14 and Dwight Howard had 12 to give Philadelphia's second unit a boost.
"The next guy has to step up. Not sure who that is going to be yet," coach Doc Rivers said after the win Friday.
ESPN Staff Writer Dave McMenamin contributed to this report.