WALTHAM, Mass. -- The Boston Celtics opened Monday's evening practice -- the second session of Day 3 of training camp -- with an emphasis on defense as players were thrown into odd-man (3-on-2 and 2-on-1) drills.

While it will come as no surprise that the offense dominated much of the exercise, it was a late defensive pairing of Jae Crowder and Amir Johnson who proved to be most noteworthy. The duo came up with a long string of stops, frustrating teammates with their activity, and that left Crowder barking and playfully cussing at his teammates about the duo's defensive prowess.

Isaiah Thomas gave it right back to Crowder when he finally broke the shutout with a 3-pointer to end the drill, but clearly coach Brad Stevens liked what he saw in the brief sequence.

Stevens has often stressed that defense must be Boston's backbone. He's challenged his team in recent years to try to shuffle toward the top 10 in defensive rating. Boston finished in a three-way tie for 12th overall last season with Utah and Philadelphia, allowing 102.1 points per 100 possessions (though that number went down to 100.3 after the All-Star break, which tied for eighth-best in the NBA in that span).

Where might Boston land this season?

"I said it the other day -- it’s going to be a canned answer -- somewhere in the top 30," Stevens quipped. "If we play well, we’ll have a chance to be higher. If we don’t, if we take shortcuts, we won’t be in the top 20. If we play really hard and really focused than the sky is the limit."

Three more notes from Monday's access at the team's training facility:

• Praise for Amir: Before Johnson's strong showing alongside Crowder, Stevens was asked how much Johnson can help Boston's defense. “He adds. And we need him to add," the coach said. "We need all of our bigs to be good, defensively. I think the strength of our team is being able to be aggressive on the perimeter, defensively. I said that last year and I thought it was the strength of our team. But we also found some strength in being able to be versatile, especially late in the season with [Brandon] Bass, Jonas [Jerebko] and Jae guarding different positions. So that’s going to be critical. The more positions that bigs can guard, the better."

Pressed on if Johnson gives the team something it lacked last season, Stevens added, "I would say that he just plays the game the right way. I don’t want to say that we haven’t had it because I think our guys put in a good effort to try to be a good defensive team. I think we finished 12th for a reason last year. It’s not as high as you ultimately want to be, but it was good strides. But he gives us a great deal of effort, and he gives us a great deal of understanding, awareness and athleticism. So it’s a great combination when you’re talking about that end of the floor."

• Zeller throws down: Second-round pick Jordan Mickey comes with a reputation for being a quality rim protector, but the rookie found out the hard way it's hard to stop a 7-footer with momentum during an odd-man rush. During one defensive drill, poor Mickey went up to challenge Tyler Zeller streaking in on the right side, only to get dunked on. ... Fellow rookies Terry Rozier and R.J. Hunter shot the ball well at times during the drills. Check out a couple of their highlights here and here.

• No standouts: Stevens hesitated to offer too much praise for any one player or lineup while stressing that the team hasn't done enough to this point to fairly judge. "We throw a lot at them in the first couple of days," said Stevens. "That’s why there’s not really a standout yet because we’re not into competing enough to really have a huge sample size there. So it’s more about just getting what we need to in and at the same time get conditioned enough to play a game." Asked again later if anyone had surprised him, Stevens added: "Not really. I've got high expectations for all of them. So I say that as a compliment to them, not as a [negative]. Again, I’m more focused on the whole right now than I am on the individuals. We’ll start really focusing on that as they play [Tuesday] night because I won't coach either of the teams. I’ll just watch. And then after that we’ll start to talk more about how we want to progress with lineups and such."

• The Celtics will host their annual season-ticket holder practice on Tuesday night at TD Garden. Stevens said the plan is to engage in three eight-minute scrimmages. It will be the first time reporters will get a glimpse at 5-on-5 action since camp opened.