MILWAUKEE — Marjon Beauchamp finished with 18 points and eight rebounds to lead host Milwaukee in the teams' preseason opener.
Giannis Antetokounmpo and Damian Lillard both sat out for the Bucks, but his older brother Thanasis Antetokounmpo totaled 14 points, five rebounds and two blocks in 21 minutes.
Malik Beasley scored 13 points and Brook Lopez scored 11 points in 12 minutes for the Bucks.
Coby White had 14 points, six rebounds and six assists to pace the Bulls, playing a team-high 23 minutes.
Patrick Williams scored 13 points for the Bulls, who used all 20 of their available players. Only guard Lonzo Ball, who will miss the season with knee issues, didn't play.