Luka Doncic smiles a lot.

It's a polarizing facial expression when it comes to sports -- critics will see it as a symbol of frivolity, a lack of toughness. While others will use the grins as evidence of a true passion for the game, an unteachable desire that's necessary to thrive at the highest levels.

"A lot of times when I don't smile, when I'm not having fun playing the game, then I play bad," Doncic said last season. "I think that's a little bit of a secret for me."

Doncic smiled plenty while dropping 34 points (one off his career high) in the Dallas Mavericks' 108-100 season-opening win on Wednesday night. Against a porous Wizards defense, the 20 year old did pretty much whatever he wanted, scoring 20 first-half points on a devilish assortment of dribble-drives and step-backs. He finished 12-of-19 from the field, including 4-of-9 from 3-point range, adding nine rebounds and three assists.

But the moments where Doncic wasn't smiling are what should really have Dallas fans excited.

From the opening tip, Wizards All-Star Bradley Beal made it his personal mission to get under Doncic's skin. Beal was extremely physical, intentionally getting in Doncic's way as he tried to run down court and attempting to slap the ball out of his hands after the whistle blew, in addition to other veteran tactics.

"It's hoops ... He understood what it was. We weren't fighting," Beal said after the game. "It's just basketball, trying to frustrate him. He was kicking our butts, so we had to do something."

It's something Doncic will have to get used to now that he's no longer a rookie and is officially an MVP candidate (and not just to the Mavs fans chanting it toward the end of the game) with a large target square on his back.

Doncic's reaction to Beal's strategy was nearly flawless all game long. He fought back just enough without going too far (as Beal did when he was ejected after receiving two consecutive technicals in the fourth quarter), and Doncic only seemed to get better as the intensity and physicality picked up. Perhaps this shouldn't be a surprise since Doncic has been playing professional basketball since puberty and was a EuroLeague champion and MVP at the ripe age of 18. He's used to getting pushed around by older, more experienced players.

"It's just basketball. I like the way he plays," Doncic said after the win about his confrontations with Beal. "He's obviously offensively a great player, but you see what he can do on defense. After he got ejected, he said to me, 'It's just basketball, you know?' And I really appreciate that. On the floor you don't have friends, so it's basketball."

Overall it was a great first game for the soon-to-be-superstar (if he's not there already). We know Doncic will put up huge numbers in his second season as the Mavericks vie for a playoff spot with the other franchise cornerstone, Kristaps Porzingis, looking healthy and spry. But the way he reacts to defenses getting more aggressive with him this season, both physically and emotionally, will partly determine how successful the Mavericks can be.

So far, so good.