"I got in at 4 a.m.," Thomas said of his second flight to Washington in two weeks. "It's tough, but it's the playoffs so there are no excuses. I decided to play and I just tried to give it all for my team."
The Celtics star flew to the funeral with Boston president of basketball operations Danny Ainge and assistant coach Jerome Allen.
During player introductions, Thomas pointed to the TD Garden rafters when his name was called.
Al Horford added 21 points, 10 rebounds and nine assists. Jae Crowder finished with career playoff-high 24 points.
Game 2 is set for Wednesday NZT.
The Wizards were more energetic at the outset, jumping out to a 16-0 advantage and leading by as many as 17 points. But the Celtics rallied with Thomas briefly sidelined while getting his tooth repositioned in the second quarter.
"I didn't know if we'd ever score and I didn't know if they've ever stop scoring," Celtics coach Brad Stevens said.
Bradley Beal led Washington with 27 points. John Wall added 20 points and 16 assists.
Washington starter Markieff Morris played just 11 minutes before leaving with a sprained left ankle in the second quarter after landing awkwardly on Horford's foot.
The Wizards also had a tough time responding after Stevens started Marcus Smart in place of Gerald Green in the third quarter.
"They were a little more aggressive than we were," Beal said. "Our defense slipped a little. We lacked some IQ and focus."
A rivalry has been simmering between the teams since last year, when Boston swept the season series.
They split their four regular-season matchups this season, but each included intense moments.
Today's matchup was played at just as high a level, with a frenzied pace at times and physical play underneath the basket.
After the Wizards' early scoring flurry, Thomas lost his tooth but initially kept playing. He found it during a timeout, but started the second quarter in the locker room. His teammates went on a 13-2 run without him to cut into Washington's lead. Boston led by 15 by the end of the third.
