Al Horford says the Boston Celtics would not be in the Eastern Conference Finals were it not for the performances of Jaylen Brown and Jayson Tatum.

The Celtics sealed a 4-1 playoff series win over the Philadelphia 76ers thanks to a thrilling 114-112 victory in Wednesday's game five.

Brown scored 24 points, while Tatum added 25 and four assists as the Celtics continued to show their depth in the absence of Kyrie Irving and Gordon Hayward.

And Horford praised the young duo for their impact in helping the Celtics to secure a showdown with the Cleveland Cavaliers and LeBron James.

"Jaylen just has that growth mindset," said Horford. "He keeps getting better.

"It's no surprise we're in this position, because if him and Tatum weren't growing as players, we couldn't have got to this point.

"People from the outside probably expected not much out of us, but I've seen the way these guys prepare and the way they train, and they want to be great."

Tatum was asked how the Celtics plan to deal with the threat of James, but the 20-year-old rookie said there is plenty of time to work on that.

"It is my first year. I don't have the answer," he said. 

"I am going to enjoy this tonight and then go to practice tomorrow and figure it out."