James made a single free throw with 36.4 seconds to play, capping his 41-point night and helping the Cleveland Cavaliers escape TD Garden with a 122-121 triumph on Friday night.
The Celtics had a final gasp after generating a defensive stop with 7 seconds to play, but a bad dribble prevented Rajon Rondo from getting off a final shot before time expired.
James scored on three consecutive late-game trips at one point over the final two minutes. That included generating an old-fashioned, three-point play with 71 seconds remaining that pushed the Cavaliers out front despite trailing by as much as 19 earlier in the quarter.
James' late-game heroics negated what was otherwise an encouraging effort from the Celtics.
Rondo had made the third quarter his playground. In less than 8 ½ minutes of floor time, he posted two points (a nifty bank shot that punctuated Boston's offensive outburst), nine assists and three rebounds. Rondo was plus-15 as the Celtics scored 42 points and opened a 17-point lead heading to the fourth quarter.
Rondo finished with 6 points, 16 assists and 8 rebounds.
• Kyri3333: The Celtics had all the momentum heading to the final frame, but Kyrie Irving single-handedly made things interesting again. Irving made a trio of 3-pointers, then got fouled in the act of shooting another and made three freebies, while scoring 12 points in under three minutes and trimming Boston's lead to single digits. James took care of the rest.
• Something in reserve: The Celtics' bench put three players in double figures (while former Cavaliers center Tyler Zeller added eight more). That bench output included 12 points from Marcus Thornton, back after missing one game with a sprained right ankle.
• Climbing the ladder: With his first assist of the game, Rondo shuffled past Paul Pierce into fourth place all time on the Celtics' all-time assists leaders. He still needs 2,623 helpers to catch Bob Cousy (and whether he re-signs here this summer could dictate whether he climbs any higher on the Celtics' list).
• What it means: The Celtics fall to 3-5 and will be kicking themselves for letting this one slip away. Boston had what should have been an insurmountable lead, but Irving's early-fourth-quarter offense gave the Cavaliers life. But it only hammers home the difference between a contender and a rebuilding squad.