BOSTON -- Boston's rising stars stalled The Process and led the Celtics to victory in Game 1 of the Eastern Conference semifinals.
Substitute point guard Terry Rozier scored 29, and first-year Celtics forward Jayson Tatum had a career-high 28 points to outplay redshirt rookie Ben Simmons on Monday night and lead Boston to a 117-101 victory over the Philadelphia 76ers.
With much of the attention focused on 76ers youngsters Simmons and Joel Embiid, Boston's youth movement of Tatum and Rozier led the way. Two days after scoring a career playoff-high 26 points in Game 7 against Milwaukee, Rozier topped it, while also adding eight rebounds and six assists.
"It's been a dream come true. I want to keep going," said Rozier, who was wearing a Drew Bledsoe Patriots jersey to milk one more chuckle out of his pseudo-feud with vanquished Bucks guard Eric Bledsoe. "I'm just a guy just living in the moment."
Embiid scored 31 points with 13 rebounds for Philadelphia, which lost for just the second time in 22 games. Simmons, the likely rookie of the year, scored 18 with seven boards and six assists.
But with six days of rest since eliminating Miami, the 76ers missed 15 of their first 20 shots and hit 5 of 26 from 3-point range to lose for just the second time since March 13.
"We're NBA players and we have to be ready," Embiid said. "We weren't ready tonight."
Al Horford had 26 points and seven rebounds for Boston, which will host Game 2 on Thursday night. The Celtics are hoping to have guard Jaylen Brown back from a hamstring injury he sustained in the clincher against the Bucks, leaving him sidelined along with Kyrie Irving and Gordon Hayward.
Playing in place of Irving, Rozier picked up where he left off in the first round by scoring 10 points and six assists in the first quarter on Monday night. He was 7 for 9 from 3-point range overall, combining with Tatum to overshadow the lottery picks accumulated by Philadelphia during The Process.
The first overall pick in the 2016 draft who sat out all of last year with an injury, Simmons was heckled by the Boston crowd with chants of "Not a Rookie!" In the fourth quarter, as Tatum stepped to the free throw line to protect a double-digit lead, the chant turned to "He's a Rookie!"
"I love when people talk trash," Embiid said. "Keep bringing it, and we'll see how it goes."
Tatum was Boston's first pick last year -- third overall -- after swapping the No. 1 pick to the Sixers and grabbing a 2018 first-rounder as well. Philadelphia picked Markelle Fultz; he did not play on Monday night.
"It's been great to see Jayson and Terry and just our guys play like that," Horford said. "I think that Jayson's starting to figure it out. ... And it's great to see for our team."
It was 33-all with just over seven minutes left in the half when the Celtics ran off 10 points in a row. Horford had four of the five baskets and assisted on the other. Boston led 87-70 in the final minute of the third quarter when Philadelphia scored nine straight points to make it a nine-point game.
After Simmons made a layup to make it 97-88, Horford hit a 3 from the top of the key with 5:30 left and it was never within single digits again.
PUT ME IN COACH
Up until about an hour before game time, Brown was still trying to figure out a way to play on his strained right hamstring.
The Celtics' second-leading scorer in the first round with 17.9 points per game, Brown was finally ruled out about a half-hour before tipoff following a conversation with doctors, trainers and Horford.
"Jaylen's a competitor, I know he was doing everything he could to be out there," Horford said. "His health is most important. We didn't want any setbacks with him. One of the things when I talked to him, I was like `Hey, we obviously really need you out there, but we need you for the long run. We need you to be healthy and to feel good.'
"Hopefully now he has a couple of day to recover and he'll be back Thursday."
OLD SCHOOL FEEL
Sixers coach Brett Brown is familiar with the Philadelphia and Boston matchups of the 1980s, having grown up in South Portland, Maine. Though he knows other teams in the East remain relevant, he thinks there is enough young talent on the current 76ers and Celtics rosters to give the rivalry a rebirth.
"I hope so," Brown said. "I personally grew up with this rivalry, just right on your doorstep and just a big part of your basketball life as a young kid. It sure seems like both programs are heading into the right direction."
Sixers: Embiid is the first Sixer with 30 points in a playoff game since Andre Miller in 2009. He is the first one with at least 30 points and 10 rebounds in a postseason game since Allen Iverson in 2001. ... Embiid again wore the mask he has needed since missing 10 straight games -- including the first two of the playoffs.
Celtics: It was the first time that Boston has had three players score 25 or more points in a playoff game since Ray Allen, Paul Pierce and Rajon Rondo in 2009. ... Hall of Famer and 11-time NBA champion Bill Russell was in the crowd.... Smart missed his first five shots. ... The Celtics put T-shirts on every seat that said "BEAT PHILA." The "L-A" were in bold, a nod to the longtime rivalry with the Lakers.
This story has been corrected in the 6th paragraph to indicate the 76ers missed 15 of their first 20 shots, not the Heat.