Rookie Jayson Tatum scored the go-ahead layup with 22 seconds remaining in the fourth as the Boston Celtics punched their ticket to the NBA Eastern Conference finals with a 114-112 win over Philadelphia.

Tatum made it 111-109 after catching a pass from Marcus Smart under the basket and Terry Rozier helped seal the win by making a pair of clutch free throws with nine seconds left as the Celtics eliminated the 76ers four games to one.

“We got a lot of heart and a lot of talent on this team, nobody expected us to get this far,” said Tatum.

The Celtics advance to the NBA’s final four to face LeBron James and the Cleveland Cavaliers for the second straight year for a berth in the finals.

Boston was coming off a defeat in game four, but managed to impose their will on the 76ers down the stretch in Wednesday’s thriller, improving to 7-0 on their home court in these playoffs.

The 76ers made the Celtics work in a game that featured 21 lead changes.

But Philadelphia had dropped the first three games and were ultimately unable to become the first team to rally from 0-3 down to win an NBA playoff series. Teams have now gone 130-0 when leading 3-0.

Forward Tatum tallied 25 points, guard Jaylen Brown had 24 and Rozier finished with 17 points and six rebounds for the Celtics who are 37-0 when taking a 2-0 lead in a playoff series.

Joel Embiid and Dario Saric, of Croatia, each scored 27 points, while Australia’s Ben Simmons finished with 18 points and eight rebounds and six assists for Philadelphia, who are 0-15 when losing the first two games of a series.

Tatum’s moment of recknoning

Tatum is the second rookie this post-season to notch seven straight 20-plus point playoff games. He joined Utah’s Donovan Mitchell, who did it over the first two rounds for a Jazz team ousted by the Houston Rockets on Tuesday.

Embiid had an opportunity to tie it after Tatum’s layup but was guarded closely and missed the shot. He grabbed his own rebound but lost that too when Rozier slapped the ball away with 10.8 seconds remaining.

Rozier made it 113-109 with his free throws but then a J.J. Reddick’s three pointer got the 76ers back to one point with 3.8 seconds left.

Smart went to the line and missed his first free throw. He tried to miss the second which would have run the clock down but it rattled in stopping time and allowing Philadelphia to try one more play. The 76ers then attempted a Hail Mary pass down the length of the court but it was intercepted by Smart who had raced back to defend after his bungled free.

“That’s a Marcus Smart sequence,” said Brown of his Celtic teammate. “The first guy back and he makes the steal. He didn’t care if he runs into somebody or hurts himself.”

Embiid ditches mask

Embiid, who was wearing a black oval mask to protect his face because of a fracture, took the vizard off for the final sequence.

“The thought was this could be the last possession of the season. I was against all the doctors but I had to toss it aside,” Embiid said.

Both the Celtics and Cavaliers have undergone roster overhauls since the Cleveland ousted the Celtics in five games last year. Only four players on each side remain from that series.

The Conference finals are now set as the East series begins Sunday at the Boston Garden and the West on Monday when the Houston Rockets host the Golden State Warriors.

Asked how the Celtics were going to shutdown James, Tatum gave his honest reply, “It is my first year. I don’t have the answer. I am going to enjoy this tonight and then go to practice tomorrow and figure it out.”

Al Horford said they will be ready.

“People from the outside probably didn’t expect much from us. But I’ve seen the way these guys prepare and they want to be great.”