With seven minutes left in the third quarter of Game 3, the Boston Celtics held a 10-point lead and looked poised to get on the board in their second-round playoff series against the Miami Heat. Just 10 seconds later, it looked like Boston's season could be over.

When the final buzzer sounded an hour after that, though, the defending Eastern Conference champions were looking very much alive.

Things change quickly in the NBA Playoffs.

The Celtics scored a 97-81 victory over the Heat before a capacity crowd at the TD Garden on Saturday night. The win cuts Miami's series lead in half and changes momentum in the Eastern Conference Semifinals after the Heat took the series' first two games in South Beach.

After managing just 22 points on 38 percent shooting at the American Airlines Arena in Games 1 and 2, Kevin Garnett turned in a masterful performance on the home parquet. Garnett repeatedly dominated Miami's frontline in the low post, scoring 28 points on 13-for-20 shooting and hauling in 18 rebounds, his most since Dec. 7, 2008, in nearly 38 minutes of play.

"I felt like I've been nonexistent pretty much offensively in this series," Garnett said in a postgame press conference. "Tonight was a little more focused on offense versus defense ... They weren't bringing a double-team, so I just took my opportunities and I was aggressive."

Paul Pierce teamed with Garnett to dominate the affair, shaking off his Game 1 ejection and Game 2 Achilles injury to come out firing with 12 first-quarter points that set the tone for Boston. The Celtics captain finished with 27 points (9-for-20, 5-for-7 from 3-point range), five rebounds and five assists in the win.

Despite their phenomenal evenings, the future Hall-of-Famers were overshadowed by the late-game performance of Boston point guard Rajon Rondo — or, more to the point, that he performed at all.

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With the Celtics leading 60-50 and 7:02 on the clock in the third quarter, Rondo — the orchestrator of the Celtics' half-court offense and one of the only clear matchup advantages that Doc Rivers possesses against Erik Spoelstra's athletically gifted squad — got tied up with Heat star Dwyane Wade. As the two tumbled to the court, Rondo extended his left arm to brace himself. The fall was awkward; the way his elbow bent was worse.

"I knew something was wrong," Rondo said in his postgame press conference. "Thank God for Kevin — I was having trouble breathing, and Kevin just kept telling me to breathe."

Rondo immediately grabbed the arm, and Garnett and his other teammates crowded around him and the Celtics medical staff swooped in. It looked bad. It looked broken.

"I still haven't seen it — I've heard I don't want to see it," Rivers said in his postgame press conference. "I've never seen the [Joe] Theismann injury, and I don't plan on seeing this one."

(If, like Doc, you didn't see it, you can see it here. Frankly, I wouldn't recommend it. It's pretty gruesome.)

Helped by the training team, a shaky Rondo walked back to the locker room; the official injury report lists team physician Dr. Brian McKeon's diagnosis as a dislocated left elbow. At that point, the prospect of continuing the series without their starting point guard seemed very real, and very daunting, for the Celtics.

Mere minutes later, though, after having his elbow popped back into place by the Celtics medical staff, Rondo returned to the Boston bench. By the start of the fourth quarter, he was back on the court and running the show, dribbling almost exclusively with his right hand as his left arm hung by his side. (Rivers said that not having seen the play probably helped him, "because if I had, from what I hear, it would've been tough to put him back in the game.")

Later, Rondo would get a bit more feeling back, using his injured left arm to steal the ball from Heat forward Chris Bosh before finishing the play by dunking with his right hand.

"I wasn't doing much offensively, but I thought I could keep the game, or change the game's momentum, by getting to the ball defensively," Rondo said after the game. "I just need two legs for that."

Rondo didn't post a great stat line, finishing with 6 points on 3-for-7 shooting, 11 assists and five turnovers in 35 minutes. But nearly 20 years to the day after Larry Bird came back from an injury to spark a Celtics playoff win over the Indiana Pacers, Rondo's return gave a major boost to teammates like Delonte West, who had hurt his left shoulder in the second quarter.

"Well, when he came back, I said, 'Well, I definitely have no excuse [not to play] now," said West, who continued to be the Celtics' steadiest — and, at many times, sole — second-unit asset, contributing 11 key points and three assists off the Boston bench.

"Shorty's a real tough dude — I've seen him play through some hellafied injuries," Garnett said of Rondo after the game. "I don't know what he's going to look like when he's 35, but right now, he's playing through a lot. He's showing a lot of heart, a lot of grit [and] we see it. That doesn't go unspoken or unseen. We see he's out there giving his full effort; we're following that lead."

Miami did have its chances in Game 3. The Heat weathered Boston's blistering first-quarter shooting (62.5 percent for the C's in the opening frame) to take a 46-44 lead into halftime. But keyed by Garnett, the Celtics were red-hot on both ends of the floor in the third quarter, finishing the stanza with an 11-point lead that they'd never relinquish.

"It's very difficult, especially against a team like this," to play uphill, LeBron James said after the game. "Even in the last series against [the Philadelphia 76ers] ... we come out and teams know something we don't know to start the third and we get down. We can't do that."

After taking turns leading the Heat as the best players on the court in Games 1 and 2, Wade and James ceded that title to Garnett for Game 3. Miami's dynamic duo combined to score 38 points on 14-for-35 shooting, mitigating their 11 assists with 7 turnovers and failing to take over the game to stop Boston's momentum.

"[Boston] is a championship team; they play with that championship DNA that they have," Wade said after the game. "We understand that it wasn't going to be easy, especially winning here. We come back Monday and try to do it again."

Running buddy Chris Bosh, much lauded for winning his power-forward matchup with Garnett in Miami, was virtually nonexistent in Boston, missing five of his six field-goal attempts for a whisper-quiet six points with five rebounds.

Bosh played the game with a pinched nerve in his neck. Asked during a brief postgame session with reporters how he sustained the injury, he said, "I woke up." Asked if he woke up with a crick in his neck, he said, "Yes. Something like that. Yes."

For long stretches, the Heat's best performers were reserves. Center Joel Anthony continued his strong play in the middle, grabbing 11 rebounds and hitting six of seven shots for 12 points (one off his career high), while point guard Mario Chalmers added 17 points on 7-for-9 shooting, four rebounds, three assists and three steals. Once again, the backups outperformed starters Zydrunas Ilgauskas (two points, two rebounds, two assists, two turnovers and a -19 in just under 10 minutes) and Mike Bibby (zero points, one assist, one turnover and a -18 in 17 minutes).

Given the mounting evidence that his best lineups put Anthony and Chalmers on the floor and leave Ilgauskas and Bibby on the bench, Spoelstra was asked after the game if he'd juggle his starting lineup for Game 4.

"I will evaluate everything," he said. "A to Z."

Game 4 tips in Boston at 7 p.m. Eastern time on Monday night.