Philadelphia 76ers starting guard Danny Green exited Friday night's 127-111 win over the Hawks in Game 3 of the Eastern Conference semifinals series because of a right calf strain and did not return.
The 12-year veteran will undergo an MRI on his calf on Saturday, sources told ESPN.
"It's a calf injury. Just my doctor's degree, I would tell you that calf injuries aren't great," Sixers coach Doc Rivers said after the game.
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," Rivers said. "I'm not ruling Danny out, but I'm pretty much ruling him out. I doubt if he plays the next game."
Korkmaz started the second half in Green's place. The Sixers are 32-7 this season with a starting lineup of Green, Joel Embiid, Ben Simmons, Tobias Harris and Seth Curry, according to data compiled by ESPN Stats & Information.
"I don't know the situation about Danny right now but it doesn't matter who is in, who is out, we just need to step up. I just need to step up if I need to and I will do it," said Korkmaz, who started 11 games during the regular season. "I am ready. I hope it's not serious. I hope we're going to get everybody healthy. But if he's out, I'm definitely ready to step up."
The Sixers took a 2-1 series lead. Game 4 is Monday in Atlanta.