MIAMI -- The Boston Celtics' practice at American Airlines Arena ended with coach Jim O'Brien demanding three "perfect" defensive stops from both the starters and the second unit.

When there was some uncertainty about whether one group had achieved perfection, O'Brien was not amused. "There's no debate here," he said, rattling off very specific criteria for textbook Celtics defense. With a four-game losing streak to stop, O'Brien was not in a playful mood.