CLEVELAND -- “It was the best of times. It was the worst of times.”

Those words from Charles Dickens seem to fit perfectly to describe the Cleveland Cavaliers’ performance against the top-seeded Boston Celtics in Game 3 of the Eastern Conference Finals at Quicken Loans Arena Sunday night.

Up by as many as 21 points in the third quarter, the Cavaliers managed to score just 42 after halftime in a 111-108 loss to the Celtics.

“Momentum. We didn't continue to press the tempo,” Cavaliers small forward LeBron James said. “Marcus Smart started to hit a lot of threes. They started to get momentum, and that's what happens -- you give a team a life. They played so freely without IT, and they just made play after play after play, and we couldn't weather the storm.”

Down by as many as 21 points after a basket from center Tristan Thompson with 6:39 to play in the third quarter, the Celtics stormed back and cut the deficit to just five, 87-82, heading into the fourth period.

The Celtics finished out the third quarter on a 26-10 run over the final six-plus minutes and outpaced the Cavaliers, 32-21, out of the halftime break.

Boston knocked down 11 of its 24 looks from the field, including six of 11 from three-point range, while the Cavaliers made only five of their 18 attempts and missed all six of their triple tries in the third quarter.

The Cavaliers’ “Big Three” of James, point guard Kyrie Irving and power forward Kevin Love combined for just 13 points in the third quarter after having 47 in the first half.

“I don't know about comfortable, but only making two threes in the second half, scoring 21 in the third and 21 in the fourth, that's not us offensively,” Cavaliers coach Tyronn Lue said. “Not shooting the basketball well, not scoring well, it happens. But when that happens, you've got to be able to get stops, especially being up 20 points.”

After making 14 of their first 22 looks from long distance, the Cavaliers made just two of their 11 attempts from three-point range in the fourth quarter, both from shooting guard J.R. Smith over the last five-plus minutes of play, and just two of 17 following the halftime break.

Conversely, the Celtics buried five of their 11 three-point tries in the fourth quarter.

Boston’s final three-pointer came when guard Avery Bradley rimmed in a shot from the left wing with 0.1 seconds remaining. Bradley caught a pass on a reverse from guard Marcus Smart and buried the game-winning triple.

“We've been playing so well, but like I said, you let a team grab momentum like that, you almost knew that that last shot was going to go in,” James said. “It was like, you already knew. As soon as the ball went out of his hands, you kind of knew that shot was going to go in because of how the game was just played throughout the second half.”