Pau Gasol blocked a potential tying layup by James in the closing seconds. Jimmy Butler then broke up an inbounds pass intended for James as time expired.
The president sat courtside for most of the game as his beloved Bulls knocked off the defending Eastern Conference champions and gave coach Fred Hoiberg a narrow win in his first game.
James scored 25 points and grabbed 10 rebounds for Cleveland, but the Cavaliers came up short against the team they knocked out in the conference semifinals last season.