Antetokounmpo also missed Milwaukee's win in Game 5 after he suffered a hyperextended left knee late in Game 4. Sources have told ESPN's Adrian Wojnarowski and Zach Lowe that a timetable for Antetokounmpo's return is unclear.
The Bucks, trying to reach the Finals for the first time since 1974, have a 3-2 lead in the Eastern Conference finals.
Bobby Portis was expected to get his second straight playoff start after scoring 22 points and grabbing eight rebounds in Milwaukee's 123-112 victory Thursday night.
"Another Day, Another Opportunity," Young posted to Twitter on Saturday afternoon.
Veteran sixth man Lou Williams started the past two games for the Hawks.
Hawks guard Bogdan Bogdanovic is listed as probable with right knee soreness, though he has yet to miss a game this postseason with the ongoing issue.
The Associated Press contributed to this report.