The Cavs will have hoped to put a miserable March in the rear-view mirror with their 122-105 victory over the hapless Philadelphia 76ers.
LeBron James scored 34 points, Kyrie Irving added 24 and Kevin Love contributed 18 in the victory, which followed on the heels of a three-game losing streak.
"We needed this game, we needed to get this win," admitted Irving after the Cavs completed a 7-10 March.
The Cavs had lost three stright, and five of their previous seven going into the contest, but Irving said the turnaround, with the playoffs a fortnight away, was under way.
"We've got to keep building from here and not look back," he said. "I'm excited about it."
LeBron James of the Cleveland Cavaliers shoots during the first half against the Philadelphia 76ers at Quicken Loans Arena
The Cavs struggles opened the door for the Celtics, and they have seized their opportunity.
Two free throws from Al Horford with 1:22 remaining proved the difference in Boston's 117-116 victory over the Orlando Magic, which kept them one-half game ahead of the Cavs atop the East.
The Celtics' 15th win in their last 17 home games wasn't certain until Amir Johnson contested Elfrid Payton's drive in the closing minutes. Payton missed, and Horford grabbed the rebound.
Isaiah Thomas scored 35 points and handed out seven assists for the Celtics, who notched their 49th win of the season -- their most since the 2010-11 campaign.
"It was a crazy finish," Thomas said. "But we kept our composure and got stops when we needed it."
Warriors rally past Rockets
Stephen Curry led the Warriors with a game-high 24 points as the Western Conference leaders notched a 10th straight win, 107-98 over the Rockets
Western Conference leaders Golden State notched a 10th straight win, throttling Houston's potent offense as they rallied late for a 107-98 victory over the Rockets.
The Warriors used a 12-0 fourth-quarter scoring run that included 10 points from their bench players.
They held the Rockets scoreless for almost seven minutes of the final period as they notched their second win over Houston in four days.
Stephen Curry led the Warriors with a game-high 24 points. Klay Thompson had 20 points and eight rebounds for the Warriors, who had 49 points from their reserves.
Curry said defensive intensity was the key.
"Even against a high-octane offense like Houston, try to keep them under a hundred points -- make it tough on them," he said of the Warriors' mindset.
James Harden led Huston with 17 points. He pulled down 12 rebounds and handed out eight assists, but missed 14 of his 18 shots overall as the Rockets lost their third straight and dropped a half-game closer to Utah in the battle for the third seed in the West.
The Warriors maintained a 3 1/2 game lead over the San Antonio Spurs atop the West.
The Spurs, with 28 points from Kawhi Leonard, 17 from Pau Gasol and 14 from LaMarcus Aldridge, withstood Oklahoma City guard Russell Westbrook's 39th triple-double of the season to beat the Thunder 100-95.
"We needed one like this," Ginobili said of the hard-fought victory. "We didn't play good for 30 minutes of the game. But we bounced back, we played aggressive, we stayed together."
Westbrook finished with 32 points, 15 rebounds and 12 assists. He's within sight of Oscar Robertson's NBA record of 41 triple-doubles in a season.
But he said he's more concerned that the defeat taught his Thunder teammates what kind of challenges they'll face when the playoffs roll around.
"Every night is going to be like this and they have to be ready," he said.
The Memphis Grizzlies are headed back to the post-season for the seventh straight year after a 99-90 victory over the Dallas Mavericks.
Mike Conley scored 28 points and Zach Randolph added 22 for the Grizzlies, who were assured of a playoff berth with the win and Denver's 122-114 defeat at Charlotte.
Grizzlies first-year coach David Fizdale said he was relieved to clinch the playoff berth with six games remaining.
"There were moments during the season when there was a lot of doubt," he said.