BOSTON (AP) -- It was his sister's birthday.
She would have been 23.
Isaiah Thomas spent four or five hours in the dentist's chair having work done on the tooth that was knocked out in Game 1, a day after he was in oral surgery for six hours having it repositioned in his mouth. His mouth was swollen, and he could barely talk. Still, he never considered not playing Tuesday night.
"The least I can do is go out there and play for her," Thomas said after scoring 53 points -- the second-highest total in Celtics playoff history -- to lead Boston to a 129-119 overtime victory over the Washington Wizards.
"I knew once game-time came, my guys would get me going, get me the energy to go out and win a game," Thomas said, ducking his face into his hands as he mentioned his sister, Chyna, who died in a car crash on the eve of the playoffs. "There was no way I was sitting out."
Fiddling with his new mouth guard throughout the game, Thomas scored 20 points in the fourth quarter and nine in overtime to help the Celtics take a 2-0 lead in the best-of-seven Eastern Conference semifinals. The 53 points were the most in an NBA playoff game since Allen Iverson scored 55 in 2003, and just one shy of John Havlicek's franchise postseason record of 54.
"It's nice to be in Celtics history with all the great players," Thomas said. "But until you win a championship, you can't consider yourself a great player. That's what it's all about."
John Wall scored 40 points with 13 assists for Washington, which will host Games 3 and 4 on Thursday and Sunday.
"Two teams played their hearts out. Two great players played well," Wizards coach Scott Brooks said. "
Asked if he had ever been in a one-on-one scoring battle like that against another point guard, Wall shook his head: "Nah," he said. "Nope. Nope. Nope."
Thomas attended his sister's funeral on Saturday and returned to Boston early Sunday morning -- just hours before the Celtics won 123-111 and the diminutive point guard lost a tooth. Team doctors jammed it back in, but Thomas spent large parts of the next two days in oral surgery.
"What else is there to say?" Celtics coach Brad Stevens asked. "There was a point today where he was not feeling good at all. He's had a tough day and I thought he was going to really have to gut this one out. Not only guts it out, he ends up with 50. Pretty impressive."
Al Horford scored 15 points with 12 rebounds for Boston, and Avery Bradley and Jae Crowder scored 14 apiece. Marcin Gortat had 14 points and 10 rebounds and Markieff Morris scored 16 for the Wizards, but both fouled out in overtime.
One game after the Wizards scored the first 16 points of the game, they erupted for 42 points in the first quarter and opened a 13-point lead. Wall had 19 in the first to 15 for Thomas, but Boston erased the deficit in the second quarter and took a brief lead with just over a minute left before the half.
Otto Porter Jr. hit a 3-pointer to give the Wizards a 114-112 lead with 33 seconds left in the fourth. Thomas made two free throws to tie it, then both Wall and Bradley Beal missed short jumpers that could have won it in regulation.
The game was only about a minute old when Morris threw Horford into the crowd under the Celtics basket. Late in the first, Wall had to shake it off after landing on a prone Kelly Olynyk. Bradley sustained a hip pointer in a collision with 1:11 to play in the first half. And seconds later, Porter landed hard on his right wrist and elbow, but remained in the game.
Thomas banged his face on the court in the third and spent the next few minutes adjusting his teeth.
Midway through the third, Porter and Thomas appeared to bang heads, and Porter headed to the locker room gushing blood from the nose. Thomas and Morris got into it, drawing double technicals; Thomas appeared to be having words with someone on the Wizards bench, and Morris tried to push him away.
Wizards: Wall's 19 first-quarter points matched a career playoff high, as did his six first-quarter assists. … Gortat fouled out going for a rebound on Boston's first possession of overtime. … Wall's 40 points in a playoff loss was the second-most in franchise history to Gilbert Arenas, who scored 44 against the Cavaliers in 2006, according to ESPN.
Celtics: Thomas had 15 points in the first quarter, followed by five in the second. … Boston shot 61 percent in the first half, but also had 10 turnovers. … New England Patriots coach Bill Belichick was at the game. So was actor David Spade. … Terry Rozier had a career playoff high with 12 points.