NBA: Grieving Thomas leads all scorers in loss to Bulls

Isaiah Thomas played with a heavy heart Sunday, scoring 33 points in a 106-102 NBA playoff loss to the Chicago Bulls just one day after his younger sister was killed in a car crash.

Thomas took to the court on an emotional night at the Boston Garden despite the death of 22-year-old Chyna Thomas, whom he honoured by pencilling her name on his green sneakers and adding "R.I.P. Lil Sis."

There was a moment of silence after the grieving Thomas led his teammates onto the floor and just before the playing of the American national anthem.

"This was difficult," said Celtics centre Al Horford. "I felt like our guys really dealt with it the right way. But Isaiah is the one who I feel dealt with it the best."

Thomas received a heart-warming standing ovation from the home crowd.

He led the Celtics with 33 points, hitting a layup with seven seconds left to cut Chicago's lead to 104-102 in the opening game of their first round playoff series.

But Chicago's Jimmy Butler dribbled off a few seconds and sealed the victory with a two free throws with just three seconds on the clock. Butler finished with 30 points.

Police said Chyna Thomas died at the scene of the accident at around 5 a.m. Saturday in Federal Way, Washington, located 35 kilometres (22 miles) south of Seattle.

Witnesses told authorities that her car drifted off the side of the road into a concrete barrier before slamming into a metal post head-on.

Isaiah Thomas was instrumental in Boston's emergence as the top seed in the NBA's Eastern Conference playoffs.