BOSTON, March 1 (Ticker) -- Antoine Walker is used to hitting big shots in Boston.

Walker scored all 13 of his points in the fourth quarter and Dwyane Wade added 24 and eight assists as the Miami Heat extended their season-high winning streak to seven games with a 103-96 victory over the Boston Celtics.

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Making his first appearance at the TD Banknorth Garden since being sent to the Heat in a blockbuster five-team trade in the offseason, Walker received a warm ovation from the crowd when he entered the game with 4:21 left in the first quarter but went on to miss his first four shots and did not score through three periods.

"I was hoping he'd miss all night," said Celtics forward Paul Pierce, who scored 38 points. "I've seen him do that, too. Hey, if they're going to beat us, we'd rather Antoine than (Shaquille O'Neal) and Dwyane Wade."

The start was reminiscent of Walker's first return to Boston, when he had a dismal performance as a member of the Dallas Mavericks during the 2003-04 campaign. However, Walker found his touch in the fourth quarter to send his former team to its third loss in eight games.

"Anytime you come back and beat your old team it has meaning," said Walker, who played the first seven campaigns of his career with the Celtics and had a short stint with the club last season. "Early in the game I didn't get the looks I wanted and rushed the early ones. In the fourth quarter, I just told myself to stay aggressive. They were doubling (Shaq) a lot, so someone else was going to have to step up and make shots."

After the Celtics used a 16-5 run to take an 86-85 lead with 5:37 remaining, Walker hit a 3-pointer to quell the rally. Rookie Ryan Gomes answered with a jumper to forge an 88-88 tie before Walker gave the Heat the lead for good with a driving layup with 4:43 left.

"I just told him to keep shooting," said O'Neal, who collected 16 points and nine rebounds. "In the fourth quarter, I knew they were going to double from his spot, so I just said, 'Go to the spot' and he made good shots."

Boston drew within a point twice and faced a 97-94 deficit after Pierce split a pair of free throws with just under two minutes to play. Shandon Anderson and Walker each grabbed offensive rebounds on the ensuing possession, allowing Walker to hit a dagger 3-pointer with 55 seconds to go.

"You could tell he wanted it, man," said Wade, who was named Eastern Conference Player of the Month earlier Wednesday. "He did a good job of willing us to victory. You have to give a lot of credit to (Antoine) for this victory."

"You have to pick your poison with them," Pierce said. "We're concentrating so much on Dwayne Wade and we're doubling Shaq that you leave a guy like Antoine open for shots, and (he's) a guy who can hurt you. That's what happens."

Pierce made two free throws, but Jason Williams all but sealed the victory with another shot from the arc with 19 seconds left. Miami made 8-of-19 3-pointers.

Delonte West made four 3-pointers and scored 12 of his 20 points in the fourth quarter for the Celtics, who were returning from a 3-1 road trip.

Wally Szczerbiak scored all 12 of his points in the first half as the Celtics grabbed a 48-46 lead. Udonis Haslem had six of his 10 in the third period to help put the Heat ahead, 73-68.

The Celtics managed just 10 points over the final 5:57 of the session, committing a pair of shot-clock violations in that span.

"That one stretch really hurt us," Celtics coach Doc Rivers said. "I thought we really lost our intensity and started to watch them play."