Jaylen Brown had 23 points and eight rebounds, Marcus Morris added 21 points and 10 boards, and the Boston Celtics opened a 21-point, first-quarter lead and beat the Cleveland Cavaliers 108-83 on Sunday in Game 1 of the Eastern Conference finals. Al Horford scored 20 points for the Celtics, who ran off 17 consecutive points in the first quarter to pull away. Game 2 is Tuesday night. Kevin Love had 17 points and eight rebounds, and LeBron James finished with 15 points, nine assists and seven boards. The Cavaliers missed their first 14 3-point attempts of the game and shot just 32 percent in the first half. By that time, Boston led 61-35 _ the biggest halftime playoff deficit in James' career.