LeBron's roundhouse throwdown floors Celts in Game 4

CLEVELAND -- We've seen dunks like that out of him before, but did you see LeBron James' face afterward? Did you see that grimace? That glare?

It was a Baddest Man on the Planet scowl that James wore on his 23-year-old face Monday night after throwing down one of the more vicious dunks that Kevin Garnett has ever been on the receiving end of.

First, James got freed by a pick and blew past Paul Pierce. Next, he made the subtlest little head fake to get James Posey leaning the wrong way, and finally, he went up over Garnett and was undeterred by the two hands KG shoved into his chest as he rose higher and higher and ultimately unleashed a windmill flush that brought the house down.

It was a virtuoso finishing act from the Eastern Conference's top superstar, a game-defining dunk that gave the Cavaliers a nine-point lead as part of their 9-2 run to close the game as Cleveland defeated Boston 88-77 to even their second-round playoff series at two games apiece.

"He can dunk. And if you give him a running start at the basket, he's going to get a good dunk. Once he gets up there, there's not a lot you can do about it," Boston coach Doc Rivers said.

James turned and started hopping back up-court after the dunk, the look on his face reminiscent of a moment two decades ago, when Mike Tyson was in his prime, knocking out Michael Spinks 91 seconds into the first round to retain the undisputed heavyweight title and run his record to an unbeaten 35-0. There wasn't an athlete like Tyson on the planet at the time, and the scariest thing about him was how ruthless and unstoppable he could be when he summoned everything he had from deep down inside.

Sort of like how James looked after that dunk over KG.

"That was the play we needed as a team," James said. "Me as an individual hadn't had a play like that, our crowd hadn't seen a play like that since the alley-oop Daniel Gibson threw to me in the first series. They deserved it, our fans deserved it, they were great, and it was great that I was able to give it to them."

James said it was his best dunk of the season, besting a flush he had over Tim Duncan because this one took place in a playoff game and the other came during the regular season.

James noted that he had shied away from Garnett on his previous drive, switching the ball from hand to hand and trying a finesse shot, and had vowed to be more aggressive on his next drive.

He sure was.

"I tried to flex like he did, but I didn't have any muscle to flex," Cavs coach Mike Brown said. "So I flexed my jaw and said 'Game 5.'"

Almost as impressive as the slam was the way James persevered through the fourth quarter, even after missing his first six shots of the quarter to drop his shooting percentage for the series below 24 percent. But he picked up his 10th and 11th assists early in the fourth on a 3-pointer by Gibson and a Joe Smith layup after a gorgeous LeBron look-away pass, and he finally knocked down a jumper when he found himself open for a 3-pointer that he finished with a long, exaggerated follow-through to push Cleveland's lead to 79-73.

A bank shot by Pierce kept Boston in it, but James fed Gibson for another 3 -- Rivers called it the biggest shot of the game -- and Pierce and Ray Allen each missed 3s on Boston's next possession before James went off for his monster dunk that all but sealed the outcome.

"The stuff he does, it shouldn't amaze you because he is who he is, but sometimes I do get giddy inside," Brown said.

The sellout crowd soon took up what has become the most popular chant of the Eastern Conference playoffs, taunting the Celtics with the same four syllables that their fans lobbed at James back in Games 1 and 2: "O-ver-rat-ed!"

That had to sting the Celtics particularly hard, because all three of their stars have been dogged throughout their careers, not by talk that they're overrated but rather by doubts about their prowess in crunch time. The big three's lines from the fourth quarter Monday read: Garnett, 0-for-2 from the field, zero points, one rebound; Allen, 0-for-1 from the field, his only a shot a 3 that never had a chance; Pierce, six points on 3-for-7 shooting, with one of Boston's two turnovers in the period.

The Celtics scored only 12 points and did not grab a single offensive rebound in the final 12 minutes, getting nothing from Sam Cassell when Rivers put him in charge of the offense for the first eight minutes of the period, and nothing from Rajon Rondo when he went in for the final 3:57.

So we've got a whole new series now, a best-of-three affair that is more and more resembling Cleveland's Eastern Conference finals series against Detroit a year ago, when the Cavs dropped the first two games, then won the next four as James single-handedly carried the Cavs to a classic Game 5 victory in Auburn Hills.

Is it happening again? Or are we merely seeing the Celtics, who were clearly the superior team over the course of the regular season, go through the playoff growing pains that any new unit must go through in its first postseason together?

The answer will be clear by the end of the weekend, with Game 5 set for Wednesday, Game 6 back here on Friday and Game 7 on Sunday in Boston, if necessary.

"Every time Cleveland gets into the postseason, we're the underdog every series we play. One day we'll earn our respect," James said.

They're earning it from the Celtics, that's for sure, and not just because of that one spectacular dunk. They're earning it through their dogged effort, both as a team and -- in James' case -- individually.

And that look on James' face after his dunk?

When someone conjures up flashbacks to the career peak of the former Baddest Man on the Planet, that guy rises another notch on the respect meter. And that's what LeBron James did on Monday night.

Chris Sheridan covers the NBA for ESPN Insider. To e-mail Chris, click here.