PHILADELPHIA (NBA.com exclusive) --  The defending Eastern Conference champion Orlando Magic and the contending Cleveland Cavaliers -- with the addition of Shaquille O'Neal -- seemed to get most of the buzz in the offseason.

It was kind of easy to forget about the Boston Celtics.

Well, the Celtics are alive and well.

They entered Tuesday's game at Philadelphia with a 4-0 record and an incredibly stingy defense allowing only 81 points per game. They left Tuesday's game with an unblemished 5-0 mark after an ultra-convincing 105-74 victory over the 76ers.

"Our defense, it's been good," Celtics coach Doc Rivers said. "The first three games, it was spectacular. The last game [against New Orleans], we played good defense, but in my opinion, we got away with it."

Even when they trailed the 76ers in the first quarter, there was never a panicked face on the court. The Celtics are aware if they can stop teams from scoring, they're going to win more often than not.

Boston simply has too many weapons to halt.

Since the beginning of the 2007-08 season, the Celtics have an 89-24 record with the starting lineup of Kendrick Perkins, Kevin Garnett, Paul Pierce, Ray Allen and Rajon Rondo. That's called consistency.

Pierce scored 21 points and Rasheed Wallace had 20, highlighted by 6 of 8 shooting from 3-point territory.

"It starts with defense for us," Perkins said. "We know we're going to get our points. The points will be there. In the Eastern Conference, it's about getting stops. Coach has been making that point since training camp. We hear him. We've seen the results."

The Celtics have depth, too.

Wallace, Marquis Daniels, Eddie House and Co. have given them a big lift in every game this season. Wallace and Daniels combined for seven points in the first quarter when they were struggling somewhat offensively. But having these interchangeable parts just makes the Celtics that much more dangerous.

For the Sixers, this was a key game early in the season. It had to be disappointing after a subpar effort.

After faltering in their opener at Orlando, they rallied for consecutive wins over the Milwaukee Bucks and New York Knicks. Last Saturday's 141-127 overtime win at Madison Square Garden was especially intriguing.

The 141 points marked the most for a Sixers team since April 1, 1990 against the Phoenix Suns. It was their first time over 130 points since the 1993-94 season.

Offense hasn't been an issue for the Sixers thus far. They'll need to lock down like the Celtics have been able to do.

The Celtics got a number of easy baskets, especially wide-open 3-pointers. They hit 14 of 20 from 3-point land while limiting the Sixers to 1 of 16. The Sixers were 0-for-11 through three quarters and 0-for-14 until rookie Jrue Holiday hit one with 1:28 remaining in the game. Holiday's basket gave the Sixers half of the point total they compiled against the Knicks.

"We understand we have to improve defensively," said Sixers forward Thaddeus Young. "We know we're capable of playing a whole lot better. We can't expect to score 141 points or well over 100 every night. There are going to be nights when it's 82-80 and we have to be prepared for games like that. Also, we have to be able to knock down shots. We realize what lies ahead for us."

Philadelphia had a difficult time forcing the Celtics out of their offense. Even when Rondo went to the bench, the offense remained fluid with House running the point. Really, the dynamics of the offense didn't change.

Wallace had 11 points in the first half, including 3-of-4 from 3-point territory. It was reminiscent of Opening Night when the Magic hit 16-of-29 of its 3-pointers against the Sixers.

"We need to keep improving in all facets, including defending the 3," Sixers guard Lou Williams said. "We'll keep working at it. Yeah, it seemed they got too many open looks on the perimeter."

The Celtics were dominant at times from the perimeter, inside the paint and in the mid-range game. They played like the veteran group they are.

And they hope the attention keeps getting directed at Orlando and Cleveland.

"Let us be a secret," Perkins said. "It's cool. Shhhh. Keep 'em quiet. I like it. I like it a lot."