Antetokounmpo left Wednesday's 127-120 loss to the Los Angeles Clippers in the second quarter after it appeared he was stepped on unintentionally by Austin Rivers. He tried to play with the injury for about a minute but then headed to the locker room and remained out of action for the rest of the game.
Antetokounmpo, 23, is having another superb season for the Bucks, averaging 27.3 points, 10.0 rebounds, 4.8 assists, 1.5 steals and 1.4 blocks per contest.
"He's our main guy," Khris Middleton said of Antetokounmpo, per Matt Velazquez of the Milwaukee Journal Sentinel. "The attention he creates on the offensive end, we definitely missed that throughout the whole game when he was out. We're a team, so when he goes out we can't give up. We know what we can do as a team, and tonight we just didn't do it."
The Bucks are 2-2 in games Antetokounmpo hasn't played in this season.
Having him out of action for any significant time would be a major blow as the team jockeys for postseason position. The Bucks (37-34) are currently eighth in the Eastern Conference, a healthy five games ahead of the ninth-place Detroit Pistons.
They are 1.5 games behind the Miami Heat for seventh, however, and climbing past Miami could mean avoiding the red-hot Toronto Raptors in the first round of the playoffs and instead facing the injury-riddled Boston Celtics.
With Antetokounmpo out of action, Jabari Parker is a prime candidate to step into the starting lineup, while Tony Snell and Muhammad could see their roles increase as well.