When his 3-pointer splashed with a half-second left in the quarter, the Cavs led 87-80.
Injured Celtics point guard Isaiah Thomas was in attendance Thursday night and gathered with his teammates in a huddle before they took the court for pregame warmups.
"(The Celtics) are giving us everything that they have, and we're expecting it, and we want the challenge", said James.
He finished the game with 35 points, booking his seventh straight finals appearance as the reigning champion Cavs wrapped up a 4-1 victory over the Celtics in the best-of-seven Eastern Conference finals.
The Celtics got the career game from Smart in Game 3, and unless someone else comes up with something similar, they aren't winning Game 5.
The Cavaliers basically conceded the East's top seed to the Celtics at the end of the regular season by opting to rest their starters in advance of the playoffs.
LeBron undaunted by challenge of facing Warriors in Finals
There was almost too much historical context to dissect, and so James did what his instincts told him to do. Can James win his fourth ring? Dating to the regular season, the Warriors have won 27 of their last 28.
They were still losing throughout, but the margin was 11 after the first quarter and 16 at halftime.
Celtics coach Brad Stevens was disappointed with his team's defense on Irving, who was able to spread the floor while surrounded by shooters. He told his charges to "outwork" the Cavs in the second half and their hosts would find a way to let them back in the game. Boston is limited in how many max contracts it can hand out while maintaining a fiscally responsible payroll; and Ainge could determine that the C's are better off using big money on scorers with more size (Gordon Hayward, Paul George or Jimmy Butler via trade) instead of Thomas. The Celtics moved the ball the way they had against Chicago and Washington in the first two rounds and found the open man. However, what's most impressive about the Nike-sponsored guard's scoring output is that he scored 19 of his points in less than five minutes after hurting his ankle in the third quarter.
The Cavs are a strong defensive team, and when they started the series, they had a defensive agenda.
The pain couldn't stop him.
The teams now travel back to Boston for game five of the series on Friday (NZ time).
James led the way with 11 points on a ideal five-for-five effort from the field. They also were outrebounded 19-17. Three-plus games is a small sample size to make any grand declarations, but it should help the C's front office make a more informed decision.
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Later in the inning, with the bases loaded and two out, Toronto left-fielder Carrera struck out for the second straight inning. Cashner had Toronto hitters stymied, particularly when they had runners in scoring position, going 0-for-7 in that situation.
However, Irving bounced back up and stayed in the game.
Start off with a return to form by James, who was poor in Game 3.
For James - who notched 24 of his 34 after half - it was his 10th game of at least 30 points, his 11th shooting at least 50 percent from the floor.
James closed it with 15 points in the fourth, including a 3-pointer with 3:52 remaining for a 106-97 lead. Only Jae Crowder (4-of-7) connected on more than one three-pointer in Game 4.
Irving said he was driven by the thought of the Cavs seeing their series lead vanish.
No surprise: Cavs-Warriors in NBA Finals, again
Durant certainly wasn't the first player to seek an instant championship through free agency. And they've added an unbelievable player in Kevin Durant this year.