WALTHAM, Mass. -- Referring to it as a natural part of the team growth process, Celtics coach Doc Rivers had his team spend the majority of Tuesday's practice session working on pick-and-roll defense. Noting that teams looking to win a title take "steps" toward that goal, Rivers said now that his team has bought in, it's focusing more on execution.

"Pick-and-roll defense. A long time on it," Rivers said of Tuesday’s session. "Teams take steps, too. To win titles, you take a lot of steps. The first step for us was buying in, and I think we've done that. But now we've got to get it right, and the second step is pick-and-roll, and it never stops. I'd love to find that team where there's perfection and you show up and say, 'Guys, we have nothing to practice on!' That will be a good day."

Rivers said he's satisfied at the moment with Boston's offense, which has put an even greater emphasis on cleaning up things on the other side of the ball. Additionally, Rivers understands the importance of his team's defense leading to a better effort on the glass.

"It's our defense. The better our defense is, the better we rebound,"

Rivers said. "There's no tricks to it. If you keep the ball out of the paint, we're a better rebounding team. If we don't have to double-team, we're a better rebounding team. If we're not scrambling in help (defense), we're a better rebounding team."

Defense, particularly of the pick-and-roll variety, will continue to be stressed Wednesday night, when the Brooklyn Nets make their first regular-season appearance at TD Garden. Not only do the Nets boast capable pick-and-roll weapons in Deron Williams, Brook Lopez and even Gerald Wallace, they have considerable size along the perimeter.

"They have size at the guard spot. You don't hear that a lot, but they do," said Rivers. "They can post up their one, which they will, a lot. They'll post up their two, and they'll post up their three. So, it's rare that you have three in that position. All three guys are post guards, and they're all shooters, too. Joe (Johnson) can shoot and Deron can do anything. But they're powerful guards, and they create a ton of problems."

Read on for more notes from Tuesday's session, including the latest on Avery Bradley and a surprise appearance by Maine-dwelling Kris Joseph and Fab Melo:

* Rivers had no update on guard Avery Bradley, who's still rehabbing from offseason shoulder surgery.

"I have no idea, honestly," Rivers said. "There probably is an update, I just haven't checked, honestly. I have no update."

It's not unusual for Rivers to not be fully up to speed on his injured players. He's employed a philosophy in which he doesn't ask until the training staff tells him the injured player is ready for more rigorous work. Bradley was initially pegged for a late-December return, and he had maintained in recent weeks that he would experiment with full-contact drills late in November.

"Honestly, he's not been in anything," Rivers said. "We are doing some things before shootarounds every once in a while where we just run our plays so he can have an idea. But, if I've learned anything, it doesn't matter how much you do skeleton offense; when you put the defense on, if you haven't played, the game, it just goes too quick and you can't remember anything. It's going to take time, even when he comes back."

* Celtics rookies Fab Melo and Kris Joseph were recalled from the Maine Red Claws, with their next game not scheduled until Friday evening against the Los Angeles D-Fenders. Joseph participated in the team's session while Melo sat out, with Rivers wanting to get some of the more experienced big men the added practice reps.

"They don't have a game and we don't have a lot of players," Rivers said. "The greatest part about (the single-team affiliation with the Red Claws) is it's an hour and a half drive, and they can drive up and practice and go back home -- I don't know what (Joseph) calls home, Boston or Maine, but it's been a pretty good thing so far for us."

Part of the Celtics' new agreement with the Red Claws allows them to send players back and forth as often as they like. So, for example, Joseph and Melo could attend the Celtics' shootaround on Friday, and then drive up and play for the Red Claws on Friday night. Joseph said he'll make the commute as often as he needs to.

"I'll go to practice in Maine and then just drive right back, if I had to," Joseph said. "It's not that far of a drive. I'm not a trucker, but it's only an hour and 40 minutes, so it's very doable."