CHICAGO — The entire night felt uncomfortable despite the Celtics leading the Bulls from start to finish, a true rarity at the United Center.

The fourth quarter began with the Celtics holding a 13-point cushion but ended with them clinging to tenuous leads and needing to execute offensively to seal the victory. They were challenged extensively by the shorthanded Bulls but the visitors passed every test, including a critical Kevin Garnett dunk that helped clinch Monday night’s 101-95 victory.