Celtics Dominate Sixers in Game 3 Drew Hallowell/Getty Images Paul Pierce, left, and Kevin Garnett of the Boston Celtics high-fiving during their game against Philadelphia on Wednesday. PHILADELPHIA - At the Boston Celtics" shootaround Wednesday morning, Coach Doc Rivers noticed a particular seriousness from point guard Rajon Rondo. It was hours before the Celtics" 107-91 victory against the Philadelphia 76ers in Game 3 of the Eastern Conference semifinals, and Rondo was already establishing the tone for his team. "I really believe we needed this game," Rondo said. We wanted to show these guys and send a message tonight. Before the Celtics and the 76ers started the series, Philadelphia appeared to be a mere speed bump on the Celtics" way to the conference finals and perhaps a postseason rematch with the Miami Heat. That perception was challenged when the eighth-seeded 76ers split two 1-point games with the Celtics and entered Game 3 with a chance to continue as the surprise of the postseason. Instead, Boston took a 2-1 series lead entering Game 4 on Friday night. "We ran into a Celtic team that had a real sense of purpose about them tonight," 76ers Coach Doug Collins said. I think they're looking at that other series a little bit, seeing Chris Bosh being out. I think they see a tremendous opportunity for themselves, and you can just see with their game tonight that is a much different team than we saw in Boston. The Celtics overpowered and outplayed Philadelphia throughout the game, quieting a crowd enlivened for the franchise's first home playoff game beyond the first round since 2003. At the time, the 76ers were paced by a single star - Allen Iverson - and a collection of supporting actors. This year's 76ers lack a true star but have thrived with a workmanlike ensemble. Thaddeus Young scored 22 points, but the 76ers could not keep pace with Boston's headliners Wednesday. Rondo finished with 23 points and 14 assists, Kevin Garnett had 27 points and 13 rebounds, and Paul Pierce recorded his best game of the series with 24 points and 12 rebounds. "I'll take it from anybody, but clearly when you game-plan for your key guys to score and they do, it makes it better for everybody else to score," Rivers said. The key to that group is Rondo, whose mastery and versatility have carved a spot for him among the N.B.A."s finest point guards in a ripe era for the position. But Rondo has seldom been a big scorer, with an average of 11.9 points a game this season and 15 points a game during the postseason. In Game 3, Rondo displayed a deft scoring touch. He scored 17 points in the first half, at times outrunning or winding through all five 76ers. At the end of the half, Rondo took a pass after Philadelphia missed a shot and drove the length of the court in four seconds to finish with a reverse layup. Rondo said he did not make any greater effort to score, but his offense allowed the other Celtics to produce. "Teams dictate their defense by trying to play off Rondo and do different things," Rivers said. When Rondo is an offensive threat, Rivers said, then Garnett, Pierce and Ray Allen "become better offensive players, because you can't spend the game playing off of him." The Celtics dominated without a big night from Allen, who had 3 points and did not reach double figures for the first time this series. There is still time for Philadelphia to recover, but Game 3 was an opportunity for either the Celtics to regroup or the 76ers to capitalize on momentum. Boston made its statement, overwhelming the 76ers and playing like the team that was expected to advance. "We wanted to come out and try to establish who we are as a team, offensively and defensively, and try to take some confidence away from them," Pierce said. We know they're a confident team, especially with the way they played us all year long and in the first two games. So I thought it was key for us to get a win like that tonight.