BOSTON – When LeBron James played his first playoff game in Boston, Celtics rookie Jaylen Brown was just 11 years old.

He added another notch Wednesday, setting the tone for the Cleveland Cavaliers with relentless attacks to the basket that methodically broke the Celtics en route to a 117-104 Game 1 victory in the Eastern Conference finals.

With nine days off giving spring to his legs, and worry about rust defining his game plan, James bull-rushed the Celtics early to help the Cavs establish a lead and snuff out any momentum the Celtics might’ve carried over from their Game 7 victory over the Washington Wizards 48 hours earlier.

The Celtics opened with a plan to switch defenders off screens to prevent James from turning the corner on drives.

James went 7-of-7 from the paint in the first quarter alone, and the Celtics’ dreams of catching the Cavs with rust were dashed when they went 0-of-8 on open 3-point shots in the first half.

Eventually the Celtics gave up and let the perimeter players stay on James, and that served only as a further green light.

The Celtics showed some fight and made a late push to make the game respectable.

James barked at the Celtics bench afterward, indicating Thomas had no chance against him.