In sharp contrast to the nail-biting contests in Boston earlier this week, the second seeds cruised past a lackluster Bulls side to grab their first lead in the best-of-seven quarter-final showdown.
"Obviously I was thrilled with the way we played," Boston head coach Doc Rivers told reporters.
"I thought our guys came out with a great defensive focus, they made great shots, and we had great energy, all game."
Veteran forward Paul Pierce top-scored for Boston with 24 points and four other Celtics reached double figures in a balanced team effort.
"Paul came out extremely aggressively. He didn't wait for them to double-team. It was beautiful," Rivers added.
Boston carved out an 11-point lead in the first quarter and a pair of three-pointers by guard Ray Allen just before half-time opened an unassailable 22-point cushion.
"We know what it takes to come in and win in someone else's house," added Celtics forward Glen Davis, who had a game-high six steals. "From here we're just trying to stay focused, but we have the momentum."
Boston shot 48 percent from the field on the night, converted turnovers into 24 points and nailed 12-of-21 three-point shots.
The Bulls struggled is every aspect of their first home playoff game in two years, hitting a series-low 63 percent from the free-throw line and just 37 percent from the field.
Poor ball movement doomed the team against the experienced Boston club, Bulls head coach Vinny Del Negro admitted.
"Twenty-two turnovers for the game is not going to get it done," Del Negro said. "They load up on the strong side and if you don't move the ball, it's going to be tough."
The tepid display silenced the sellout crowd of 23,072 and droves of red-shirted Bulls fans were already heading for the exits in the fourth quarter.
For the Bulls, guard Ben Gordon top-scored with 15 points, against his 42 in the team's narrow Game Two defeat on Monday.
"We didn't do anything right tonight. Everybody had an off night, including myself," Gordon said.
Game Four is in Chicago on Sunday.
