Stiemsma set an off-ball screen on Mayo and appeared to have slightly caught Mayo in the head. Mayo reacted immediately, throwing what looked like a forearm punch right at Stiemsma's noggin.
Here's video of the incident:
Mayo logged just three minutes and missed his only shot from the field before the incident occurred. The sixth-year guard is averaging 12.1 points and 2.3 assists in 48 games with Milwaukee.
The Bucks and Pelicans are currently in the middle of the third quarter in a two-possession game. Milwaukee is already without Ersan Ilyasova, who was suspended without pay for this game because he punched and shoved Kings big man Reggie Evans after an altercation under the basket.
Milwaukee currently owns the league's worst record (12-48) and has endured several other on- and off-court issues this season.