The fan went largely unnoticed until Chris Paul nearly ran into him while taking the ball up the floor:
Prior to getting escorted off the court by security during the Clippers' possession, the fan got close enough to touch Irving without forcing play to stop:
Here's another look:
And here's a shot of the fan "getting back on defense," courtesy of NBA.com's John Schuhmann:
It was at this point that CP3 pointed out there was a spectator taking a stroll on the court, and he was escorted out by security.
You may recall a fan in Cleveland rushed onto the court last season when the Cavs faced LeBron James and the Miami Heat. He was wearing a shirt directed at LeBron that said, "We Miss You," per Nick Schwartz of USA Today.
Also, this young fan asked Irving in October if he was going to leave Cleveland like LeBron did. Clearly there's some separation anxiety in the fanbase.
Perhaps it's time for the Cavs organization to improve security efforts to prevent this type of thing from happening in the future.