Marbury scored all 12 of his points in the fourth quarter to bring the Celtics back from the dead in a wild, come-from-behind 92-88 victory over the Magic in Game 5 of the Eastern Conference semifinals. Thanks to a much-needed spark from ``Starbury,'' Boston owns a 3-2 lead in the best-of-seven series with a chance to end it tomorrow night in Orlando.

``He's been great for us,'' Rivers said. ``He just hangs in there and keeps working every day. He's been very patient.

``This is tough for him. I'm just happy for him. I really am.''

Said Paul Pierce, ``We believe in him. That's why we picked him up. The reason why we went up, 3-2, in today's game is because of the energy he brought us in the fourth quarter.''

Marbury has been a starter since the time he picked up a Basketball in Coney Island. But entering this season with the Knicks, he went from starter to suspended as he didn't see eye-to-eye with his club. After an ugly he said/he said that went on for months, Marbury was finally able to get a buyout of his $23 million contract and signed with Boston Feb. 27.

But with budding star Rajon Rondo at point guard, there was little time available for Marbury to blow off the dust that accumulated following a layoff of more than a year. With his focus on the big picture of trying to win a championship, however, he put aside his own agenda for the betterment of the team.

``It's been very difficult,'' Marbury said. ``But for me, I think the mind-set and the focus is to see the big picture. When you look at a puzzle, what's the most important thing? A lot of guys would say different things. The picture, that's the most important thing.

``The big picture is to win a championship. Whatever is needed for me to come here and do, I was willing. It didn't matter.''

Said Pierce, ``You got to understand, he's been put in a tough situation. Doc has asked him to come in and play limited minutes. Sometimes it's four or five minutes, and it's tough to get in a rhythm. The times that he does play, I think he comes in and gives us a spark, and he played a little bit more like he did tonight and it showed some of the things he can do.''

Marbury entered Game 5 averaging 3.3 points and 1.9 assists in 11.7 minutes per game while shooting a dismal 27.5 percent from the field and 22 percent from 3-point range. Sure, there were flashes of his old self, as he scored 13 points against Chicago April 23 and 8 in just 8:49 in Game 2 against Orlando.

Marbury once said trying to get up to speed with the Celtics was like trying to compete in the New York Marathon after starting late because his registration was messed up.

``It's hard to get back in the game and try to make something happen and then you come out,'' Marbury said.

Well, in the Boston Marathon last night, the 32-year-old finally joined the pack.

Through three quarters, the Celtics were down, 67-59, and Marbury was scoreless after missing all four field goal attempts in 8:15. He re-entered with 11:22 remaining in the fourth quarter and Boston in serious trouble, behind, 69-59. But 17 seconds later, Marbury started getting it going as he nailed a 20-foot jumper.

Next was a Marbury 3-pointer, a 20-foot jumper, an assist to Glen Davis for a hook, and finally a 3-point play with 5:55 remaining that gave him a quick 12 points, and Boston was within reach at 83-75.

With 4:55 left and Orlando up 10 (85-75), Rivers made the tough decision to take out Marbury and fellow reserves Eddie House and Brian Scalabrine for the starters. With Marbury playing a little bit in strategic situations the rest of the way, Boston finished the game with a 17-3 run for a stunning 92-88 victory.

``It felt good,'' said Marbury, who made 5 of 10 shots from the field and had two assists. ``I know that we needed it and the timing was right. It was right for me to go in and do what I did for us to win the Basketball game.

``When I went into the game, my whole mind-set was to go out there and try to create something so we could change the flow of the game.''

Said Orlando coach Stan Van Gundy, ``Marbury really made us pay. He made some jump shots. He hit the three. He hasn't been a guy that's made many threes. He hit a huge one.

``Stephon stepped up and made really big shots. He was the key to the game, I thought.''

As the buzzer sounded and Celtics fans roared at a fever pitch, Marbury threw up a No. 1 sign and ran off the floor in celebration with the satisfaction of knowing that he finally proved Rivers right.

``I believe in Doc,'' he said. ``When you believe, it's totally different.''

Marc J. Spears can be reached at mspears @globe.com