Ben Stiller got dragged into a beef between tennis star Nick Kyrgios and a heckler at a famous tournament on Thursday -- and the scene was hilarious.
Here's the deal -- at one point during Kyrgios' match against Rafael Nadal at Indian Wells in California ... the Australian hit a serve that caused a fan to talk some trash.
Kyrgios fired back right away -- asking him straight up, "Are you good at tennis!?"
When the fan responded, "No," Nick went off.