CLEVELAND -- Point guard Isaiah Thomas may stand only 5-foot-9, but he is a giant in the Boston sports scene for guiding the Celtics back to the Eastern Conference Finals for the first time since the 2011-2012 season despite playing with a heavy heart.

Thomas’ sister, Chyna, was killed in a one-car crash in Federal Way, Washington, just 20 minutes from their hometown of Tacoma, on Saturday, April 15, the day before the Celtics began their first-round series with the Chicago Bulls.

“At the end of the day, basketball is easiest way to get away from anything that you may be going through, and I said that already,” Cavaliers small forward LeBron James said. “It’s a comfort.

“You see your teammates. You see the court. You see the excitement, and you’re playing something that you’ve been loving forever. Even with him going through what he’s been going through with his personal family and his sister, which I can’t put myself in his shoes, he’s been unbelievable to be able to do that.”

During the six-game series with the Chicago Bulls in the first round, Thomas averaged 23 points, 4.3 rebounds, 5.7 assists and 1.0 steals while shooting 43 percent from the field and 81.1 percent from the free-throw line. Thomas guided the Celtics to four straight wins after they lost their first two games of the series at home.

Then, against the Washington Wizards in the Eastern Conference Semifinals, Thomas elevated his play on the offensive end of the floor and scored 27.4 points and handed out 7.1 assists over an average of 36.7 minutes in the seven-game series.

Thomas shot 44.9 percent from the field and raised his three-point efficiency from 20 percent in the first round to 46.3 percent against the Wizards. He averaged better than 3.5 made three-pointers per game against the Wizards.

And in the closeout game against the Wizards, Thomas buried nine shots, including three three-pointers, and eight free throws on the way to a 29-point performance, which he credited to watching film of James against the Celtics in the 2012 NBA Playoffs.

“To each his own,” James said. “It’s whatever gets you in the mindset to go out and play. I’ve never watched previous games and things of that nature, but I think it’s to each his own. Obviously, it worked. He had a hell of a game.”

And James knows that with Thomas’ solid ball-handling skills that create a very difficult stop-and-go tempo to his drives, the Celtics will be quite the challenge in the Eastern Conference Finals.

“There’s some very, very good players that know how to do that, so it’s going to be very challenging for us defensively, but it should be,” James said. “It’s the postseason and we should want it no other way.”