The rookie sure ain't a rookie anymore.

The Celtics season is only one game old and I can already see major improvements for Jayson Tatum. I know that's probably a crazy thing to say about a kid who was almost Rookie of the Year and was arguably the best Celtics player in the playoffs last season.

Tatum came into last season as a talented kid joining a talented team. You could see that he was a little unsure of his place and his role. With injuries to Gordon Hayward, Kyrie Irving and others, he was forced to adjust to a bigger role than he and the Celtics expected. He shined all season long and exploded in the playoffs. This year, he looks like a talented kid who knows he's a talented kid and isn't afraid to go out and play his game.

In the offseason, he worked with NBA legend Kobe Bryant. Believe me when I tell you, it shows. He made it a priority to work on finishing around the basket and you can see it. In the season opener, Tatum took the ball and made the game his. He finished with 23 points and was the team's leading scorer.

He also isn't lacking in confidence at all. After taking Joel Embiid off the dribble on Tuesday and leaving him in the dust as he drained a fadeaway bank shot, he stared down Embiid and winked at him. A little swagger and showmanship from the kid tells me he's ready for primetime.

Tatum at just 20-years-old looks poised to push either Al or Gordon out of the proverbial "Big Three," and become the next Celtics superstar sooner rather than later.

Keep an eye on Tatum all season. I can almost promise you he's slowly but surely going to become your new favorite Celtic--if he isn't already.