The Cavaliers had won two straight before suffering consecutive loss to the Los Angeles Lakers, Minnesota and Washington.
James was held to 14 points, shooting just 3-for-10 after scoring eight points in first quarter, as Cleveland was routed at home 106-88 by the Wizards on Saturday.
The Cavaliers, who lead the NBA in rebounding with 46.4 per game, were outrebounded 54-39. Cavs forward Carlos Boozer, who is tied for fifth in the league with 11 boards per game, had just eight.
Despite their latest losing streak, the Cavaliers have already surpassed last season’s win total of 17.
James, who is averaging 20.6 points, said the amount of wins are an improvement, but the team Cavs need to make the playoffs for him to consider it a successful season.
“I knew a lot of people in Cleveland who didn’t think we had a chance after 20 games. Now everybody’s hyped up, thinking we have a chance,” James said.
The Celtics have not fared as well since the swap, going 11-16. Boston has lost 10 of its last 13 games and is 1-5 under interim head coach John Carroll, who replaced Jim O’Brien on Jan. 27.
Paul Pierce scored 35 points as Boston snapped a six-game losing streak with a 110-80 rout of Philadelphia on Saturday.
Davis had 20 points and Walter McCarty added 16 for Boston, which hadn’t won since beating Washington on Jan. 23.
“It wasn’t just the first win, it was the quality of the game,” Carroll said. “I just enjoyed watching our guys play basketball the way I had hoped they could play over the last week. They finally put it together and didn’t look back. It’s just great for the guys. I like to see them rewarded.”
STANDINGS (through Feb. 7): Celtics - 3rd place, 7 GB, Atlantic Division. Cavaliers - 6th place, 18 GB, Central Division.
TEAM LEADERS: Celtics - Pierce, 23.2 ppg, 6.6 rpg and 5.3 apg. Cavaliers - James, 20.6 ppg and 5.9 apg; Boozer, 11.0 rpg.
SEASON SERIES: Celtics, 3-0.
LAST MEETING: Jan. 9; Celtics, 107-82. At Boston, Pierce had 30 points, 12 rebounds and eight assists for Boston before sitting out most of the fourth quarter. James had 19 points on 7-for-19 shooting for Cleveland.
ROAD/HOME RECORDS: Celtics - 12-12 on the road; Cavaliers - 13-11 at home.
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