MIAMI -- Milwaukee Bucks star Giannis Antetokounmpo is out for Tuesday's game against the Miami Heat with a left knee effusion.

Antetokounmpo went through shootaround on Tuesday morning and did his pregame warmup routine before he felt the discomfort in his knee.

"It's breaking news to me, too, right now," Bucks coach Doc Rivers said before the game. "So we'll just wait and see."

Antetokounmpo had been probable on the team's injury report leading up to Tuesday's game despite being listed with a calf strain. He was downgraded to questionable and ruled out a few hours before the game.

Antetokounmpo has been on a tear this season, averaging a career-high 32.4 points on 60.8% shooting to go along with 11.9 rebounds and 6.4 assists. He will miss his second game of the season; he sat out in a 116-114 loss on Nov. 4 against the Cleveland Cavaliers with a right adductor strain.