LAS VEGAS -- Chinanu Onuaku just wanted to switch back onto his man.

Grant Williams would not stand for it.

The 6′7″ Celtics rookie had just picked up 6′ 11″ Marques Bolden in transition. Onuaku saw the apparent mismatch. So did Cleveland Cavaliers point guard Naz Mitrou-Long.

“Naz on the other team, he said (to Bolden)‘look who you have on you, post up,'" Williams recalled. It was then that he shot Onuaku a snarl, dismissing his teammate. "I said ‘what? Alright man, get out of the way.’

What ensued was a mismatch alright, just not the one people thought.

Bolden couldn’t take advantage. Williams bodied him, slid his feet, cut him off, and forced the pass.

“He turned the ball over and didn’t even get a shot up,” Williams boasted. “I was like, ‘man, you better ask somebody. I’m not weak. I’m not a little small guy.’ I was like, you gotta give me that credit.”

Not only did he stop a guy four inches taller, he switch onto the attacking guard after the pass.

“That’s what’s needed," Williams said. “That’s what our team is asking me to do. I have to be able to play multiple positions on the defensive end and guard guys that are smaller and larger than me, so, it’s something I take as a challenge for sure.”

A minute later, Williams was challenged again.

“On the other end they put (Anthony) Lawrence on me and I was like ‘that’s disrespectful,’” he said with a furrowed brow. “I told coach, I said ‘run it and I’ll get us a basket.'”

And he did.

He calls himself a goofball every chance he gets, but Williams isn’t going to take perceived slights laying down.

“That’s the competitive side of me,” he said, flashing his usual smile. "It comes out every now and again.”

Williams was a +20, again, for the Summer Celtics. He didn’t shoot it quite as well, but he again made the plays that turned him into the best player on the floor for a stretch where Boston needed someone to control the game.

"I didn’t really score the ball tonight and that’s something I had to do at Tennessee. But now it’s like I don’t necessarily have to score, I can impact the game in every other way,” he said. “For me it’s all about just making an impact and the value of winning.”