After three, the Bulls have an 83-76 lead. After being held scoreless in the first half, Rajon Rondo  managed to score six points in the quarter, but he also picked up three fouls and has four heading into the final quarter.
Fouls have been the story of the game so far. After five games of physical play, the refs have called a tight game. The Bulls have been in foul trouble for most of the game, but the Celtics  were able to get through the quarter with Big Baby Davis and Kenrick Perkins each keeping their fouls at three. That could be a key development in the last 12 minutes.
The other key is keeping Chicago off the offensive glass. The Bulls had six offensive rebounds in the quarter, after only one getting one in the first half.