In their game against the Brooklyn Nets, Boston Celtics head coach Brad Stevens called a timeout very early in the game.

Just 29 seconds into the game, Stevens stood up from the Celtics bench and signaled to the referees that he wanted a timeout. This was right after the Celtics turned the ball over on their opening possession, leading to the Nets converting on a three-pointer from the corner.

Center Al Horford may have been surprised by the early timeout. In the clip, he can be seen looking around as if he's wondering what just happened. It's hard to tell what Stevens saw which triggered him to gather in his players. Did he notice a lack in energy? Were his players a step behind the Nets?

The Celtics entered the game in a two-game slump on top of criticism from various basketball analysts. They don't look like a championship contender like many expect them to be. They were just one game away from the NBA Finals last season. Many expected them to power through this season, but that hasn't been the case so far.

Whatever the real reason is behind the early timeout, Stevens — regarded as one of the best coaches in the NBA — knew what he was doing.