BOSTON (AP) — Brandon Jennings had 21 points, 13 assists and six steals and the Milwaukee Bucks won their opening game for the first time in six years with a 99-88 victory over the Boston Celtics on Friday night.

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Boston Celtics guard Rajon Rondo drives to the basket against the Milwaukee Bucks in the first quarter of an NBA basketball game in Boston, Friday, Nov. 2, 2012. (AP Photo/Charles Krupa) AP

The Bucks never trailed after the first 6 minutes and led by at least 11 points throughout the second half as the Celtics, who allowed the second-fewest points in the NBA last season, struggled defensively for the second consecutive game. They lost 120-107 to the Miami Heat on Tuesday night, matching the most points they allowed in any game last season.

Boston, in its home opener, was led by Kevin Garnett with 15 points and Rajon Rondo with 14 points and 11 assists. The Celtics lost their first three games last season.

The biggest cheers of the night went to David Ortiz, the Boston Red Sox designated hitter seated in the front row at midcourt.

A baseball official with knowledge of the negotiations said the team and Ortiz had agreed to a two-year, $26 million deal. Several fans shouted “congratulations” to Ortiz as he walked to his seat early in the third quarter. A loud cheer went up when he was shown on the video scoreboard, then he raised his left arm straight up to acknowledge the crowd.

Later in the quarter, the fans booed the Celtics when Monta Ellis hit a layup after a steal by Jennings, giving the Bucks a 66-46 lead with 4:10 left in the period.

Tobias Harris scored 18 points for Milwaukee and Ellis had 14.

The Bucks led 94-72, matching their biggest lead, on a basket by Jennings with 3:45 to go in the game before the Celtics whittled the final margin down to 11 points.

In their final regular-season game last season, the Celtics beat the Bucks 87-74 before going on to the Eastern Conference finals where they lost to the Heat in seven games. The Bucks missed the playoffs.

Milwaukee took control after Paul Pierce gave Boston its last lead, 10-8, with two free throws with 6:34 left in the first quarter.

Jennings followed with a layup, Ersan Ilyasova made a short jumper and Ellis hit a dunk on a fast break for a 16-10 lead. It was 25-18 after one quarter before the Bucks held the Celtics to 12 points in the second quarter to take a 46-30 halftime lead.

Boston improved its shooting in the third quarter, hitting 56.3 percent of its shots, but committed seven turnovers that led to 10 points, and Milwaukee took a 76-58 lead heading into the fourth.

The Celtics have just six players who saw action with the team last season and are struggling defensively after holding opponents to the lowest field-goal percentage in the league, 41.9 percent. They allowed the Heat to hit 54.4 percent of their shots in the opener and the Bucks to make 46.5 percent.