-- Boston coach Doc Rivers is a firm believer in the statement: "Defense wins championships."

The Celtics ranked first in defensive field goal percentage (41.9) and second in points allowed (90.3) during their 2008 championship season, and they tied Cleveland for first in defensive field goal percentage (43.1) and finished third in points allowed (93.4) last year even though they were missing their defensive player of the year, Kevin Garnett, for most of the second half of the season.

This year they signed 4-time All-Star Rasheed Wallace, Marquis Daniels, and Shelden Williams, who all have a defensive mindset.

Over the first three days of training camp, captain Paul Pierce has been impressed with the way the Celtics have played defense so far.

"Defense is obviously ahead of the offense at this point," Pierce said. "We have our system and the guys on the offensive end are rushing and turning the ball over but [defense] is going to be the most important thing going into the year and that has been our staple the last couple of years, how we defend, so definitely defense is ahead of the offense at this point of training camp."

When Garnett went down with his right knee injury on Feb. 19 in Utah, Kendrick Perkins became the captain of the Celtics defense.

"Perk's been phenomenal," Rivers said. "He's in great shape. He's just playing well. He's doing all of the things that you're used to seeing him do. He's scoring a little bit more in the post so he's been really good."

Wallace has also been impressed with Perkins.

"I'm not sure who his high school coach was but someone taught Perk the game the right way," Wallace said. "You don't see that a whole lot with guys come straight from high school to the league and you don't see it a lot with guys going from high school to college. Someone was definitely defensive minded who taught Perk the game."

Adding Wallace to an already vocal defense between Garnett and Perkins has made the Celtics training camp very intense so far, Pierce said.

"He's played on great defensive teams, championship teams, so he understands what it takes," Pierce said of Wallace. "If we defend on high level, we're going to win on most nights."

-- In other news, Garnett (knee) and Tony Allen (ankle) participated in all of the Celtics team practice drills for the second day in a row.

-- Rivers announced that an MRI revealed that second year forward Bill Walker has a torn meniscus in his right knee and will be out for the next six to eight weeks.

"For him you feel bad because he's had, what, three or four or five surgeries," Rivers said. "It's just a bum break for him. It really is. But that's part of all this stuff, I guess, and he's becoming an expert at handling it. He's obviously down about it."