Isaiah Thomas’ postseason just keeps getting more and more improbable.

Thomas scored 53 points on Tuesday night, leading the Celtics to a thrilling 129-119 overtime victory over the Washington Wizards to stake a 2-0 lead in the series. It was the second-most points for a Boston Celtics player ever in postseason history behind John Havlicek’s 54.

And as Thomas revealed in his postgame press conference, Tuesday also would’ve been Chyna Thomas’ 23rd birthday. She was killed in a single-car accident on April 15.

“Today is my sister’s birthday,” Thomas said. “She would’ve been 23 today, so the least I can do is go out there and play for her.”

Thomas explained his emotions further immediately following the win to TNT’s David Aldridge.

“My family, my friends, they tell me to just keep going,” he said. “My sister wouldn’t want me to stop. The only thing about it is once I leave this gym, I hit reality and she’s not here. That’s the tough part. When I’m in this arena, I can lock in and I know everything I do is for her.”

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Thomas’ obstacles weren’t resigned to just heartache. He lost a front tooth in Sunday’s Game 1 win and then underwent oral surgery on Monday to try reposition it. Thomas had even more work done on his mouth ahead of Tuesday’s game to keep the swelling down.

“Today my mouth was so swollen this morning I had to go back to the hospital to get a few meds to get the swelling down,” he said after playing with a mouthguard for the first time. “I could barely talk.”

“My mouth was just kinda like, I don’t know,” he said. “It was big. I definitely wouldn’t have looked good on TV if it was still like that.”

Not only wouldn’t it have looked good, but the mouthguard, as Thomas explained, impacted his trash talking ability. It was a light moment during an otherwise grueling two weeks for Thomas.

“I like to talk trash,” Thomas said. “That’s just the game of basketball. I had to get a little used to it. I was stuttering a few times in the first half.”

Thomas, after scoring 33 in the Celtics’ Game 1 win, somehow added to the lore of his postseason run.

“It’s nice to be, your name to be in Celtics history because of all the great players but until you win one of them championships you can’t call yourself a great player until you do that.” Thomas said. “That’s the ultimate goal.”

Follow USA TODAY Sports’ Michael Singer on Twitter @msinger.