Novak came on social media and did say it was an accident, I saw 2 different angles of the video on social media, the bottle did fall out of the backpack as the fan tried to get an autograph when Novak was about to walk through the tunnel
Actually the best place for fans to get auto graphs of their favorite tennis players at the Rome tournament, is to go up to the area where the cars drop off players coming from their hotels, it has security guards, so fans dont get crushed, and the players always stop to sign autographs and have photos with the fans