BOSTON -- Shaquille O'Neal was not around when the visiting team's locker room door opened, depriving everyone of an explanation as to exactly how he hurt his thumb, how badly he hurt it and how strange it was that the game completely flip-flopped after he was gone.

The Cavs started playing faster. They started locking down on defense. The paint opened up and LeBron James used that space to draw away multiple defenders and leave Mo Williams wide open for three consecutive fourth-quarter 3-pointers that turned this tale of two halves into a steamrolling.

If you only saw the first 12 minutes, you'd be convinced the Celtics were the far superior team.

If you only saw the last 12 minutes, you'd be saying to yourself: "Geez, those Cavs sure are going to give the Lakers a tough time in the Finals."

It was one of those nights that ended so differently than the way it started, it practically begged for O'Neal to sum it up with one of his quips.

But since he absconded, we're going to have to take a page out of the Big Fella's playbook and christen this game with a nickname all its own -- one O'Neal himself would appreciate despite the turnaround coming somewhat at his expense.

"The Big Thumbthing."

If we were writing with a lisp, we'd tell you that yeth, thumbthing thuperlative happened to the Cleveland Cavaliers midway through their 108-88 victory over the Celtics as they chipped away at an early 13-point deficit, lost their big man to an injury that they would only call "significant," then put the pedal to the floor in the final 12 minutes and outscored Boston 35-14 in the fourth quarter.

The end result was a 20-point victory that should put at least a temporary halt to the debate about pinpointing exactly what ailment had befallen the Cavs since the All-Star break, which they entered with a 13-game winning streak and exited by losing three of their last four.

"It's about keeping up the momentum throughout the year and being able to go into the playoffs on a high,' James said. "You don't look too far into a regular-season game -- you want to compare yourself against those teams, because Boston's playing well, the Lakers are playing well, Orlando's playing well, so you want to see where you are at that point in time. But as far as looking too far into it, saying that if we meet them in the playoffs this is exactly what'll happen again? No, we won't do that."

O'Neal injured his right thumb midway through the second quarter, realizing the severity of the injury when he received the ball on the perimeter, tried to grip it and couldn't.

Despite playing without Paul Pierce (sprained thumb), Ray Allen was hitting from outside, Kevin Garnett had enough lift in his legs to convert one of those alley-oop dunks he had been coming up short on all season, and the Cavs' lack of defensive intensity that coach Mike Brown had railed against pregame was manifesting itself again.

Then the O'Neal injury happened, and the thought flashed through the mind: They've lost Shaq, they aren't sure if they're getting Zydrunas Ilgauskas back (actually, they're 99 percent convinced he's returning, even if they won't say so publicly), and they look like they're on the way to losing the headlock they've held on the rest of the conference since mid-December.

And then …

Boston couldn't shake 'em. And when the Cavs hit, boy, did they hit hard.

The Celtics' lead actually shrank to eight by halftime, the Cavs kept chipping away throughout the third quarter, and then Williams -- who had looked so helpless and overmatched trying to stop Rondo in the early going -- got wide open for three consecutive 3-pointers to turn an 84-80 edge into a 93-83 lead.

Cleveland's advantage never dropped below double digits after that.

"It was a little bit of both. We didn't shoot the ball well and we didn't guard well in the first half, and then, you know, the 3-point shot is a back-breaker in this league, and to get three of them from Mo, that was huge," James said.

It was especially huge considering how little Williams contributed offensively during the Cavs' playoff demise last year after he'd been chosen for the Eastern Conference All-Star team.

Williams was a combined 3-for-18 in Cleveland's previous two games, including 1-for-9 on 3-pointers, and the talk around Cleveland was that no matter how the Antawn Jamison-Anderson Varejao-J.J. Hickson timeshare ends up being resolved, it ain't gonna matter much if Mo is chipping paint off the rim.

But now?

"It does a lot for your psyche," Williams said. "More than anything this game is 90 percent mental, and your approach means everything, your confidence is everything. Talent plays a part, but you have to mentally be prepared."

So the Cavs now bring the NBA's best record (45-14) with them as they move on to Toronto for the second night of a back-to-back, knowing they won't have O'Neal for at least one game, but also knowing that their Boston bugaboo -- their inability to win there for nearly four whole years -- had been overcome.

And the way it happened? It sure was thumbthing.

Chris Sheridan covers the NBA for ESPN Insider.

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