LOS ANGELES — Even Kobe Bryant couldn't save the Los Angeles Lakers, who find themselves on the brink of elimination after one of the biggest collapses in NBA finals history.

The Lakers led Boston by as many as 24 points in the second quarter and by 20 midway through the third before the Celtics rallied for a 97-91 victory today and a 3-1 series lead.

No team has ever come back from such a deficit in the finals.

After two free throws by Vladimir Radmanovic with 6:04 left in the third quarter gave the Lakers a 70-50 lead, they were outscored 47-21 to finish the game. It all started with a 21-3 run to finish the third period.

"We just fell apart," Radmanovic said. "I have no explanation. They made a huge comeback, you have to give them credit. We'll see the tape tomorrow, see exactly what the mistakes were."

Boston's comeback was remindful of the Lakers' rally from a 95-71 deficit to draw within two points late in Game 2 before the Celtics scored the last four points for a 108-102 victory.

"Not like it. We didn't win it," Radmanovic said. "They found a way to do it."

The Celtics can win their NBA-record 17th championship Sunday night at Staples Center, where the Lakers had gone 9-0 in the postseason and won 15 straight games dating to March 28 before this improbable defeat.

Bryant shot 6-for-19 from the field and scored 10 of his 17 points in the fourth quarter. The other Lakers' starters all reached double figures, but the contributions were minimal down the stretch. Bryant shot 4-of-8 and his teammates went 4-of-13 in the final period.

According to the Elias Sports Bureau, the comeback was the biggest in the finals since 1971, surpassing Houston's comeback from a 20-point deficit to Orlando 13 years ago.

"They're very depressed about that," Lakers coach Phil Jackson said of his players. "They're resilient. They have disappointments, they come back. This is not over. The series is not over."

The odds are, however, stacked heavily against the Lakers. They have got to win Sunday night and then win twice in Boston, where the Celtics have a 12-1 record in the postseason. No team has ever overcome a 3-1 deficit in the finals.

Sasha Vujacic, a hero in the Lakers' 87-81 victory in Game 3, shot 1-for-9 and had three points in Game 4, and allowed Ray Allen to drive around him for a game-clinching layup with 16.4 seconds remaining, giving the Celtics a five-point lead.

"We had the game in control most of the game," Vujacic said. "I don't know what else to say. We're supposed to adjust to the way the game was played. We didn't. It's hard to lose like that.

"We lost. It's frustrating. It hurts. But we're not done yet."

Regarding Allen's play, Vujacic said: "Everything I did was a foul. He got me. It was a good basket. It was a bad decision on my part."

Vujacic said he was never able to find his shooting rhythm.

"I was struggling as soon as I got into the game," he said.

Lamar Odom, who struggled mightily in the first three games, came alive in this one with 19 points and 10 rebounds. But he had only four points and two rebounds in the second half.

Bryant had 10 assists, but could have had several others had the Lakers not misfired time and again in the second half. Pau Gasol, who had 17 points and 10 rebounds, failed to convert a dunk in the late going, and Jordan Farmar missed a 3-pointer with less than 3 minutes to go that could have tied the game.

The Lakers never trailed until Eddie House's jumper with 4:07 remaining put the Celtics on top 84-83. Boston never looked back after that.

Bryant had three points and three fouls in the first half, failing to make a field goal until the opening minute of the third quarter. He has made only 38 field goals in 88 attempts in the finals.