There was no slow start for Jayson Tatum on Sunday.

The Celtics star exploded for 25 first-half points en route to a historic 51-point effort to lead Boston in a 112-88 Game 7 blowout over the Philadelphia 76ers. His 51 points are the most in Game 7 history, passing a 50-point mark that Golden State Warriors guard Stephen Curry set just two weeks prior against the Sacramento Kings.

In a matchup featuring reigning MVP Joel Embiid, Tatum was easily the best player on the court as the Celtics eliminated their longtime rivals from the postseason. Boston advances to face the Miami Heat in the Eastern Conference finals for a second consecutive season.

76ers control game early before Harden flagrant foul

The game looked like anything but a blowout in a first half that favored Philadelphia early. The 76ers took a 29-23 first-quarter lead thanks in part to an 11-point effort from P.J. Tucker, who surpassed his previous playoff scoring high of 9 points in the game's first 12 minutes. Tatum matched Tucker with 11 in a sign of bigger things to come.

The 76ers remained in control early in the second. But a flagrant foul on James Harden saw the tide turn in Boston's favor with 8:26 remaining. Harden attacked the basket in transition with Jaylen Brown defending. As Brown jumped to contest Harden's layup attempt, Harden reached out with his right hand, connecting with Brown's face. Brown tumbled into the basket stanchion.

Officials reviewed the play and issued a flagrant 1 foul on Harden for the contact that took place with Philadelphia leading, 35-27. Instead of a transition layup for Philadelphia, the play resulted in free throws and possession for Boston. The Celtics capitalized with two made three throws by Brown and a Robert Williams alley-oop dunk for a 4-point Boston possession. The sequence sparked an 8-0 Celtics run that saw Boston tie the game at 35-35.

Tatum takes control

Then Tatum took over. He scored 12 points in the final 5:15 of the half, including a step-back 3-pointer with 31.4 seconds remaining to give the Celtics a 55-52 halftime lead.

After the break, Boston blew the game open. Tatum scored baskets on consecutive possessions in the third quarter's opening minutes including another 3-pointer to extend Boston's lead to 62-55. The bucket prompted a timeout from 76ers head coach Doc Rivers. It was to no avail.

76ers disappear after halftime

Sparked by a 28-3 run, the Celtics outscored the 76ers, 33-10 in the third quarter to take an 88-62 lead into the fourth. The 10-point third was tied for the lowest scoring output in a playoff game in the NBA's shot clock era. Tatum outscored the 76ers on his own in the third with 17 points in the stanza.

There was no 76ers response to close the gap. Tatum added 9 more points in the fourth before leaving the game to a curtain call with 3:23 remaining and Boston leading 108-78. His dominant effort came on the heels of slow starts in multiple games this series, including a 1-of-14 effort to start Game 6. But he bounced back for 16 points in the fourth quarter in Game 6 to rally the Celtics to a win and force Sunday's Game 7.

Tatum finished with 51 points, 13 rebounds, 5 assists and 2 steals. He connected on 17-of-28 field-goal attempts including a 6-of-10 effort from 3-point distance. Brown added 25 points, 6 rebounds, 2 assists, 2 steals and 2 blocks while shooting 9 of 19 from the field and 3 of 6 from 3.

Embiid, meanwhile was no match for his All-NBA counterpart. The 76ers center tallied 15 points, 8 rebounds and 2 blocks while shooting 5 of 18 from the field. Harden tallied 9 points, 7 assists and 6 rebounds on a 3-of-11 shooting effort. He shot 1 for 5 from 3-point distance.

The Celtics shot 47.1% from the field and 15 of 33 (45.5%) from 3-point distance. The 76ers shot 37.3% from the field and 8 of 37 (21.6%) from 3. Boston outrebounded Philadelphia, 43-37 and won the turnover margin, 7 to 12.

Rivers falls to 6-10 in Games 7 as a head coach with five more Game 7 losses than any other coach in NBA history. Philadelphia has now been eliminated short of the conference finals for a sixth straight season. Boston's Joe Mazzulla advances to the conference finals in his first season as an NBA head coach after inheriting the defending Eastern Conference finalists from exiled head coach Ime Udoka in the offseason.

Boston will look to replicate last season's conference finals victory over a Heat team that's won two playoff series as the East's No. 8 seed. Game 1 is scheduled to tip Wednesday night in Boston.