PHILADELPHIA -- As he considered a question about whether the Boston Celtics should have called a timeout to set up their final possession at the end of regulation or in overtime of a 116-115 loss to the Philadelphia 76ers in Game 4 on Sunday, star Jayson Tatum recalled how the strategy paid off a year earlier.

Then, with the Celtics down by one at the end on the final possession against the Brooklyn Nets in the first round of the 2022 NBA playoffs, Boston rebounded a miss from Kevin Durant and went on offense without calling a timeout, leading to a game-winning layup from Tatum in the final seconds.

So, even though the buzzer sounded on Sunday, at the end of overtime, before Marcus Smart could release a 3-pointer that would have been the game-winner, the Celtics were content with their late game execution -- besides the fact that Tatum added he should have started the play a moment faster.

"You've got to trust the guys on the floor are going to make the right plays," Tatum said during his postgame media availability. "I should've passed it probably a second earlier (in overtime), but at the end of regulation, got a great shot.

"Sometimes the ball goes in, sometimes it doesn't, but we got a good core group of guys that know how to play, especially in those situations. It just doesn't always go your way."

The Celtics almost stole Game 4 despite falling behind by 16 points and giving up a game-high 42-points to James Harden. Still, Boston had a pair of chances to win the game on the final possession at the end of the fourth quarter and in overtime.

After overcoming a nine-point deficit at the start of the fourth quarter to tie the game, the Celtics inbounded the ball with 16.1 seconds remaining and elected not to call a timeout to set up the final play. Tatum's drive generated an open 3-pointer from Smart, but he missed to send the game into overtime.

Then in overtime, Harden hit the go-ahead 3-pointer with 19.0 seconds remaining, but the Celtics once again decided to attack without stopping the game. But Tatum does not begin his drive toward the basket until there are less than five seconds remaining. He finds Smart for an open 3-pointer, but the clock expires before Smart, who makes the shot, lets go of the ball.

"We had the right matchup," Celtics coach Joe Mazzulla said. "Jayson got downhill and made the right play at the rim. We just have to play with a little more pace there."

Added Smart: "It was close. Good look. Great read by JT. Made a good play, made it, just not in time."

The series is tied at 2-2. Game 5 is Tuesday night in Boston.

Even though the Celtics lost on Sunday, they left Philadelphia with a few things to be encouraged with. Tatum finished with 24 points, 18 rebounds and six assists with four blocks, a playoff career high in both rebounds and blocks.

After a slow start with two points in the first half, he shot 8-for-11 in the second half. Al Horford finished with five blocks in the game, including three on Joel Embiid in the fourth quarter, the first player to block Embiid three times in a single quarter in his career.

But after Celtics guard Jaylen Brown made everything difficult for Harden as the Sixers star struggled in Games 2&3, Harden got going in Game 4 once Brown got in early foul trouble. Meanwhile, after scoring 12 points in the first five minutes Brown did not have much of an impact over the rest of the game, scoring just 11 points the rest of the way, including three shots in the fourth quarter and overtime.

And yet, despite the loss, Horford said he was feeling optimistic by the way the Celtics rallied to have a chance to win the game on the final play.

"We knew we were going to get their best shot today," Horford said. "They put it out there and we were able to withstand it. Weren't able to close the game, but I'm pretty proud of our group and how we responded today."